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BRIDGE  AT  HELL  GATE,  NEW  YORK.   SPAN  1,000  FEET. 

For  description  see   page  89. 


ARTISTIC 
BRIDGE   DESIGN 


A  SYSTEMATIC  TREATISE 

ON  THE  DESIGN  OF  MODERN  BRIDGES 

ACCORDING    TO    AESTHETIC    PRINCIPLES 


BY 

HENRY  GRATTAN  TYRRELL.  C.  E. 

(Toronto  University) 
Bridge  and  Structural  Engineer 

AUTHOR  OF 

Mill  Building  Construction  (1900);   Concrete  Bridges  and  Culverts;   History  of 
Bridge  Engineering;    Mill  Buildings    (1910) 


WITH  AN  INTRODUCTION  BY 

THOMAS  HASTINGS 
of  Carrere  &  Hastings,  Architects 


BOSTON  COLLEGE  LiBRARr 
CHESTNUT-HILL,  MASS. 


CHICAGO 
THE  MYRON  C  CLARK  PUBLISHING  CO. 


Copyrighted  1912 

BY 

HENEY  GEATTAN  TYEEELLo 


"Xl^ 


PREFACE 

A  lack  of  artistic  treatment  is  the  greatest  fault  of  American 
bridges.  These  structures  are  worthy  of  greater  thought  and 
study  because  they  are  usually  such  conspicuous  objects  in  the 
landscape.  The  lack  of  art  is  no  doubt  partly  due  to  the 
dearth  of  literature  on  the  subject  and  the  difficulty  in  securing 
good  illustrations,  and  it  is  hoped  that  this  book  will  assist  in 
producing  better  results. 

The  most  important  work  in  connection  with  any  great 
building  enterprise  is  the  preparation  of  the  design,  for  on  this 
the  success  or  failure  of  the  project  depends.  If  the  design 
is  faulty,  the  money,  time  and  thought  spent  on  its  construction 
are  largely  wasted,  and  all  the  labor  of  engineers,  contractors 
and  artisans  is  lost.  If  the  design  is  lacking  in  beauty,  the  struc- 
ture may  remain  for  centuries  as  a  mockery  to  its  originators,, 
unless  fortunately  it  should  collapse  through  structural  weak- 
ness and  give  place  to  another  one,  more  worthy. 

The  impression  has  long  prevailed  that  bridge  design  con- 
sists in  the  development  of  formulae,  the  solution  of  problems 
in  graphic  statics  and  the  computation  of  stresses  in  truss 
frames;  whereas,  this  is  not  design  at  all,  but  merely  a  part 
of  the  process  in  producing  a  design.  Almost  no  attention 
has  been  given  by  engineers  in  America  to  the  artistic  character 
of  bridges,  and  but  little  to  their  proper  proportions,  or  to  the 
selection  of  economic  types.  For  fifty  years  mathematicians 
wrestled  with  purely  constructive  problems,  evolving  formulae 
and  establishing  tlieir  conclusions,  and  in  this  direction  there 
is  little  left  to  be  desired;  but  during  this  time  little  improve- 
ment was  made  in  the  visible  appearance  of  their  creations. 
It  remains,  therefore,  for  the  engineers  of  the  twentieth  cen- 
tury to  insist  upon  and  to  establish  a  higher  standard  of  bridge  y 


/ 


PREFACE 

design,  based  upon  the  combined  standards  of  economic  propor- 
tions and  aesthetic  appearance.  Engineers  are  frequently  defi- 
cient in  artistic  training  and  taste,  and  architects  in  constructive 
knowledge,  and  the  need  of  improvement  is  generally  admitted. 
The  tendency  in  this  direction  is  shown  by  the  cooperation 
between  engineers  and  architects  on  many  of  the  largest  struc- 
tures, particularly  the  proposed  bridges  for  New  York  and 
Washington. 

Mr.'Gustav  Lindenthal,  who  is  an  unquestioned  authority 
on  bridge  building,  says:  "It  cannot  be  denied  that  America 
is  behind  the  standards  of  Europe  in  aesthetic  construction. 
There,  the  more  important  bridges,  particularly  in  cities,  are 
invariably  designed  with  a  view  to  their  architectural  appear- 
ance. Details  of  construction  are  subordmated  to  it.  The 
American  practice  is  regulated  more  from  the  standpoint  of 
utility,  of  quick  fabrication  and  speedy  erection,  not  always 
with  the  happiest  results  architecturally.  Although  the  United 
States  has  the  largest  number  of  steel  and  iron  bridges,  it  has 
also  the  distinction  of  having  the  ugliest.  There  are  certain 
indications,  however,  of  an  improvement  in  taste  and  it  is  entirely 
within  the  possibilities  of  the  near  future  that  American  engi- 
neers will  be  able  in  foreign  competitions  to  furnish  designs  for 
bridges  at  once  architecturally  meritorious  and  economic  of 
cost." 

During  the  writer's  twenty-five  years  experience  he  has 
made  designs  for  several  hundred  bridges,  many  of  which  were 
built,  and  the  suggestions  in  this  book  are  the  outcome  of  his 
effort  and  study  to  control  dominant  commercialism  which  has 
caused  engineers  to  perpetrate  so  much  vandalism.  The  book 
is  the  development  of  a  series  of  articles  on  ornamental  bridge 
construction,  written  by  him  and  published  in  The  American 
Architect  in  1901,  though  more  than  fifty  half-tones  used  in 
those  articles  have  not  been  reproduced  here.  The  number  of 
illustrations  might  easily  have  been  increased,  only  a  few  being 
included  from  the  writer's  collection  of  more  than  a  thousand 
photographs.     Certain  principles  of  design  have  occasionally 


PREFACE 

been  repeated  in  different  chapters,  where  it  appeared  desirable 
for  the  sake  of  emphasis  or  clearness. 

There  is  perhaps  no  one  better  able  to  write  on  the  subject 
than  Mr.  Thomas  Hastings,  who  has  furnished  the  introductory 
chapter,  for  the  work  of  his  firm,  Carrere  &  Hastings,  on  the 
great  bridges  of  New  York,  is  very  well  known.  I  have 
received  valuable  suggestions  and  illustrations  also  from  Mr. 
Whitney  Warren,  architect  of  the  proposed  Hudson  Memorial 
bridge,  and  from  Mr.  Paul  Pelz,  architect  in  chief  of  the  Con- 
gressional Library,  and  designer  of  the  proposed  Potomac 
Memorial  bridges  at  Washington. 

In  the  preparation  of  this  work,  I  have  been  assisted  by 
my  wife,  Maude  K.  Tyrrell,  who  is  a  graduate  of  the  Chicago 
Art  Institute,  with  practical  experience  in  architectural  design. 

Some  illustrations  of  European  bridges  were  supplied  to 
mc  complimentarily  by  the  "Gutehoffnungshiitte"  of  Ober- 
hausen,  Germany,  and  a  few  others  were  secured  from  The 
Concrete-Steel  Engineering  Company  of  New  York.  Benefit 
has  been  derived  from  discussions  and  illustrations  which  have 
appeared  in  various  periodicals  and  journals,  including  The 
Engineer  and  Engineering  of  London,  Genie  Civil,  Annales 
des  Ponts  et  Chaussees,  Revue  Industrielle,  Nouvelles  Annales 
de  la  Construction,  Revista  de  Obras  Publicas,  Glaser's 
Annaien  fiir  Gewerbe  und  Bauwesen,  Zeitschrift  fiir 
Bauwesen,  Zentralblatt  der  Bauverwaltung,  Beton  und  Eisen, 
Stahl  und  Eisen,  Zeitschrift  des  Vereines  Deutscher  Ingenieure, 
Zeitschrift  der  Oesterreichischen  Ingenieur  und  Architeckten 
Verein,  Allgemeine  Bauzeitung,  Deutsche  Bauzeitung,  An- 
nales des  travaux  publics  de  Belgique,  De  Ingenieur, 
Tijdschrift  van  het.  K.  Inst,  van  Ing.,  Schweizerische  Bauzei- 
tung, Giornale  del  Genio  Civile,  Engineering  News,  Engineer- 
ing Record,  Metropolitan  Magazine,  Architectural  Record, 
Scientific  American,  etc.,  as  well  as  reports  from  many  Ameri- 
can and  foreign  technical  and  scientific  societies. 

Evanston,  Illinois,  H.  G.  Tyrrell. 

August,  191 1. 


TABLE  OF  CONTENTS 


Introduction  by  Thomas  Hastings 
chapter  page 

I      Importance  of  Bridges 9 

Magnitude  of  Subject 11 

Relation  of  Bridges  to  Progress 13 

II      Reasons  for  Art  in  Bridges 16 

III  Standards  of  Art  in  Bridges 19 

IV  Causes  for  Lack  of  Art 24 

V      Special  Features  of  Bridges 29 

Kinds  of  Bridges  and  Comparative  Merits 32 

Selection  of  Proper  Type 34 

VI      Principles  of  Design 3o 

Cooperation  of  Engineer  and  Architect 38 

General  Dimensions 41 

Piers 41 

General  Principles 42 

Expressiveness    . 44 

Symmetry  and  Simplicity 45 

Harmony  and  Contrast 46 

Conformity  with  Environment 47 

Materials  and  Colors 48 

Use  of  Ornament 49 

VII   Ordinary  Steel  Structures 30 

Beam  Bridges 50 

Truss  Bridges 53 

Viaducts  and  Trestles 55 

Movable  Bridges 56 

VIII      Cantilever  Bridges 67 

Number  of  Spans 67 

Chord  Outline .  69 

Ornament 73 

IX      Metal  Arches 75 

The  Deck 75 

Spandrel  Framing 75 

Relative  Elevations  of  Deck  and  Springs 11 

Arch  Types 77 

Pins  or  Hinges 81 

Arch  Forms 84 


X  CONTENTS 

CHAPTER  PAGE 

Piers  or  Towers , ,  ,  ,  87 

Approaches ...,...,. ,  .  88 

Ornament 89 

X      Suspension    Bridges 90 

Types 91 

Number  of  Spans 93 

Towers    93 

Cables , 97 

Method  of  Stiffening  Cables 99 

Rigid  Suspensions    1 00 

Anchorages 1  00 

XI  Masonry  Bridges 101 

Arrangement  and  Length  of  Spans 101 

The  Deck 1  03 

Spandrels 1  04 

Arch   Ring ...  1 06 

Shape  and  Proportion 107 

Piers    109 

Space  Above  Piers 112 

Abutments .  113 

Parapets  and  Balustrades 117 

Material,  Color  and  Surface  Finish ...........  125 

XII  Illustrations  and  Descriptions I  30 


LIST  OF  ILLUSTRATIONS 


Frontispiece .  .Proposed  Hell  Gate  Arch,  New  York 

FIGURE  PAGE 

1  Native  Bridge  in  Peru „ 9 

2  Indian  Bridge,   British  Columbia.  . 10 

3  Proposed    English   Channel    Bridge 12 

4  Old   London   Bridge 13 

5  Ponte   Rotto,   Rome 14 

6  Parallel  Chord  Truss 16 

7  Winona   Cantilever 18 

8  Sunderland  Bridge  over  the  Wear 21 

9  Bridge   at  Portland,    Pa .  22 

10  Whipple  Truss 27 

1  1  Ponte  Vecchio,  Florence 29 

1 2  Saint  Chamas   Bridge 30 

1 3  Valentre  Bridge  at  Cahors 30 

14  Memorial  Bridge,  Capitol  Park,  Hartford 31 

I  5  Auteuil  Viaduct,   Paris 32 

16  Britannia    Bridge,   England 33 

1 7  Forest   Hills    Entrance,    Boston 34 

1 8  Plauen    Stone    Arch 34 

19  Belle   Isle   Park   Bridge,   Detroit 37 

20  Spuyten  Duyvil,  Proposed  Hudson  Memorial 39 

21  Memorial  Bridge  at  Washington,  D.  C.    (Proposed)  ....  40 

22  Memorial  Bridge  at  Washington,  D.  C.   (Proposed)  ....  40 

23  Bridge  in  Fayal,  Azores •  •  .  42 

24  Forest  Park  Entrance,  St.  Louis,  Mo 43 

25  Madison,  N.  J.,  Park  Bridge 43 

26  Design  for  Bridge  in  Fairmount  Park,   Philadelphia.  ...  44 

II  Meadow  Street  Bridge,  Pittsburg,  Pa 45 

28  Walnut  Lane  Bridge,   Philadelphia 46 

29  Proposed  St.   Lawrence  River  Arch 47 

30  Saintes    Bridge    48 

31  Design  for  Short  Span  Beam  Bridge 51 

32  Design  for  Short  Span  Beam  Bridge 51 

33  Proposed  Concrete  Beam  Bridge  over  the  Jordan 52 

34  Elizabethtown  Bridge  over  Great  Miami  River 53 

35  New  Baltimore   Bridge,  Ohio 53 

36  Kuilenburg  Bridge,   Holland 53 

37  Montreal  River  Viaduct 54 

38  Lethbridge  Viaduct,  Alberta,  Canada 54 

39  Proposed  Salmon  River  Trestle,   Idaho 55 

40  Viaduct  at  Ogden,   Utah 55 


xii  LIST  OF  ILLUSTRATIONS 

FIGURE  PAGE 

41  Belah  Viaduct,  England 56 

42  La    Double   Viaduct 56 

43  Double  Leaf  Bascule  Bridge 57 

44  Proposed  Bridge  at  Washington 58 

45  Proposed  Bridge  at  Washington 58 

46  Spanish    Bascule 60 

47  Spanish    Bascule    Tower 62 

48  Webster    Avenue    Swing    Bridge,    Chicago 63 

49  Bridge  Over  the  Connecticut  River  at  Middletown 64 

50  Proposed  Design  for  the  Quebec  Bridge,  by  Mr.  Fidler.  .  68 

5 1  Queensborough,    or    Blackwell's    Island    Cantilever,    New 

York     68 

52  Hooghly  Cantilever 69 

53  Cernavoda  Cantilever 69 

54  Villefranche  Cantilever 70 

55  Bridge  over  the  Firth  of  Forth,  Scotland 70 

56  Weser  River  Bridge  at  Hameln 70 

57  Proposed  Bridge  over  Salmon  River  Gorge,  Idaho 71 

58  Proposed  Bridge  over  Salmon  River  Gorge,  Idaho 72 

59  Proposed  Bridge  over  Salmon  River  Gorge,  Idaho 72 

60  Proposed   Harlem   River   Bridge 73 

61  Sukkur   Bridge,   India 73 

62  Beaver    Cantilever 74 

63  Proposed  Salmon  River  Arch,  Idaho 76 

64  Grunenthal  Arch 77 

65  Niagara    Railroad   Arch 78 

66  Salmon  River  Bridge,  British  Columbia 78 

67  Proposed  Salmon   River  Arch,   Idaho 79 

68  Bridge  Over  the  Rhme  at  Bonn 80 

69  Duesseldorf  Bridge  over  the  Rhine 80 

70  Harburg  Bridge  over  the  Elbe 82 

7 1  Proposed  Arch  over  the  St.  Lawrence  River 81 

72  Alexander  III  Bridge  at  Paris 82 

73  The  Garabit  Arch 83 

74  Kaiser  Wilhelm  Bridge  at  Mungsten 83 

75  Yunnan  Arch,   China 84 

76  Thermopylae  Arch,  Greece 85 

11  Proposed  Arch-Cantilever   at  Mass.   Ave.,   Washington.  .  85 

78  Lincoln  Park  Arch-Cantilever,  Chicago 86 

79  Stony  Creek  Arch,  British  Columbia .  87 

80  Niagara-Chfton   Arch 89 

8 1  The  Ordish  Suspension 91 

82  The    Dredge    System    for   Suspension    Bridges 91 

83  Tower  Bridge  over  the  Thames,  London 92 

84  Cubzac  Suspension  over  the  Dordogne 92 

85  Williamsburg  Bridge  Tower,  New  York 94 

86  Roche-Bernard   Suspension 95 

87  Danube  Canal  Suspension 95 

88  Manhattan  Suspension  Bridge,  New  York 96 


LIST  OF  ILLUSTRATIONS  xiii 

FIGURE  PAGE 

89  Manhattan  Suspension  Bridge,  Mr.  Lindenthal's  Design .  .  96 

90  Proposed  North  River  Suspension 98 

9 1  Proposed  North  River  Suspension  Tower  Detail 98 

92  Proposed  Design  for  Grand  Ave.  Viaduct,  Milwaukee.  .  103 

93  Grosvenor    Bridge, ,  England 1 04 

94  Avon   Railroad   Bridge,   Indiana 105 

95  Mr.  Thacher's  Design  for  Bridge  in  Schenley   Park.  ...  106 

96  The  Topeka  Bridge 106 

97  Proposed  Railroad  Arch  in  Idaho 108 

PIER    DETAILS 

98  Pons   Fabricius,    Rome 110 

99  Rimini    Bridge,    Italy 110 

1 00  Ponte  Rotto,   Rome 110 

1 0 1  Trinity  Bridge,  Florence 110 

102  Auld  Brig  o'  Ayr,  Scotland 11 

103  Dunkeld   Bridge 11 

1 04  Tongueland    Bridge 11 

1 05  Almaraz    Bridge,    Spain 11 

1 06  Bridge  at  Mianeh,  Persia 11 

107  Fredericksbruecke,    Berlin 114 

1 08  German  Bridge 114 

1 09  French    Bridge    114 

1  10  Bridge   at   Chalons 115 

1  1  1  Pont  Marie,   France 115 

1  1 2  Pont  Morand,  at  Lyons .  115 

113  Bridge  of  Neuilly 115 

1  1 4  Pont  Lafayette 116 

1  1 5  Louis    Philippe    Bridge 116 

116  Rustic  Arch    118 

1  1  7  French  Rustic  Beam  Bridge 118 

BALUSTRADE   AND    RAILING   DETAILS 

1  1 8  Gerrard's  Hostel  Bridge 118 

1  1 9  Palissy  Bridge 118 

1 20  Bridge  over  Lea  Cut,  England 118 

121  Ely  Bridge 119 

1  22  Stone  or  Brick  Balustrade 119 

123  Stone  or  Brick  Balustrade , 119 

124  Antoinette   Bridge,   Brick   Balustrade 119 

125  Andelys    Bridge 119 

126  Eden  Park  Bridge,  Cincinnati 120 

127  Balustrade  Design 120 

1 28  Balustrade  Design 120 

1  29  Bridge  in  Garfield  Park,  Chicago 120 

1 30  Balustrade  Design 120 

1 31  Balustrade  Design 122 

132  Connecticut  Ave.  Bridge,  Washington 122 


xiv  LIST  OF  ILLUSTRATIONS 

FIGURE  PAGE 

133      Bushnell    Park,    Hartford .  .  . .  122 

1  34      Balustrade  Design 1 22 

1  35      Balustrade  Design 1 22 

1  36      Balustrade  Design 123 

1  37      Louis   Philippe,    Bridge 123 

138      Balustrade  Design .  123 

1  39      Brick  or  Stone  Balustrade .  123 

140  Stone  Balustrade 123 

141  Stone  Balustrade 1 24 

1 42  Terra  Cotta,  Concrete  or  Stone 124 

143  Italian  Renaissance  Design 124 

144  Gothic  Balustrade,  Metal  or  Tile 124 

1 45  Metal    Balustrade 124 

146  Metal    Balustrade 124 

148  Ornamental    Iron    Railing 126 

149  Metal    Railing     126 

1 50  Ornamental  Iron 126 

1 5 1  Ornamental  Iron 126 

1 52  Bordeaux   Bridge   RaiHng 126 

153  Metal    Railing    127 

1 54  Metal    Railing    127 

1 55  Metal    Railing    127 

1 56  Metal    Railing     127 

157  French    Metal    Railing 128 

158  French    Metal    Railing 128 

1  59      Design  for  Reinforced  Concrete  Arch  Bridge 128 

Bridge  Illustrations  with  Descriptions 

RUSTIC    PARK    bridges 

160  Bridge  in  Japanese  Tea  Garden,  San  Francisco 131 

161  Bridge  in  Minneapolis  Park 1  33 

1  62      Log  Arch  at  Washington,  D.  C 135 

STONE    PARK    BRIDGES 

163      Bridge  at  Belle  Isle  Park,  Detroit,  Mii:h 137 

1  64      Arch  Bridge  in  Garfield  Park,  Chicago 1  39 

165  Brick  Arch,  Lake  Park,  Milwaukee 141 

1 66  Longwood    Bridge,    Boston 143 

167  Forest  Hills  Entrance,  Franklin  Park,   Boston 145 

168  Stony    Brook    Bridge,    Boston 147 

CONCRETE    PARK    BRIDGES 

169  Stockbridge,  Mass.,  Foot  Bridge 149 

1  70      Lake   Park,    Milwaukee,    Foot   Bridge 151 

1  71       Bridge  in  Union  Park,  Chicago,  111 153 

1  72      Boulder-Faced  Bridge,  Washington    155 

1  73      Bridge  in  Yellowstone  National   Park 157 


LIST  OF  ILLUSTRATIONS  xv 

FIGURE  PAGE 

1 74     Eden  Park,   Cincinnati 157 

1  75      Bridge  at  Hyde  Park  on  Hudson 1  59 

1  76      Bridge  at  Hyde  Park  on  Hudson 159 

1 11      Como   Park   Entrance,   St.    Paul 161 

1  78      Newell  Avenue  Bridge,   New  York 163 

1  79     Columbian  Park  Bridge,  Lafayette,  Ind 1  65 

METAL    PARK    BRIDGES 

180  Madison,   N.  J.,   Park  Bridge 167 

181  Lion  Bridges,  Lake  Park,  Milwaukee 169 

SUSPENSION    PARK    BRIDGES 

1 82  Bridge  in   Boston   Public  Garden 171 

1 83  Garfield  Park  Suspension,  Chicago 173 

STONE   ARCH    BRIDGES 

184  Pont  du  Gard 1  75 

1 85  Karlsbruecke    177 

186  Alcantara  Bridge  at  Toledo,  Spain 1  79 

187  The  Rialto,  Venice 181 

1 88  London  Bridge 183 

1 89  Cabin  John  Bridge,  Washington 185 

1 90  High  Brfdge,   New  York 187 

191  Echo  Bridge,  Newton  Mass 189 

1 92  Wissahickon  Railroad   Bridge 191 

193  Interlaken   Bridge,   Minneapolis 193 

194  Chatsworth  Bridge,  England 195 

REINFORCED    CONCRETE    BRIDGES 

195  Proposed  Hudson  Memorial,  New  York 197 

196  Walnut  Lane  Bridge,   Philadelphia 199 

197  Proposed  Potomac  River  Memorial  Bridge 201 

198  Proposed  Potomac  River  Memorial  Bridge 203 

199  Rocky   River   Bridge,   Cleveland 205 

200  Big  Muddy  River  Bridge,  Illinois 207 

201  Double  Track  Railroad  Bridse 209 

202  Zanesville,   Ohio,   Y   Bridge 211 

203  Washington  Street  Bridge,   Dayton,   Ohio 211 

204  Jamestown   Exposition    Bridge 213 

205  Highway   Bridge,   Marion  County,   Indiana 215 

206  Newark,   N.   J.,    Bridge 217 

207  Concrete  Bridge  at  Grand  Rapids,   Mich 219 

208  Morris  Street  Bridge  over  White  River,  Indianapolis.  ...  221 

209  Northwestern   Avenue    Bridge,    Indianapolis 223 

210  White  River  Bridge  at  Emerichsville 225 

21  1      The   Topeka   Bridge,   Kansas 227 

212  Wayne  Street  Bridge,  Peru,  Ind 229 

213  Green  Island  Bridge,   Niagara  Falls 231 

214  Niagara  Falls  Reinforced  Concrete   Bridge 233 


xvi  LIST  OF  ILLUSTRATIONS 

FIGURE  PAGE 

2\5  Maumee  River   Bridge,   Waterville,   Ohio 235 

2 1  6  Bridge   at   Derby,   Conn 237 

METAL   ARCH    BRIDGES 

217  Proposed  Hudson  Memorial  Steel  Arch.     No.   1 239 

2 1  8  Proposed  Hudson  Memorial  Steel  Arch.     No.  2 24 1 

219  Proposed  Grant  Memorial  Bridge,  Washington.     No.   1  .  .  243 

220  Proposed  Grant  Memorial  Bridge,  Washington.     No.  2  .  .  245 

221  Niagara-Clifton    Highway    Arch 245 

222  Stony  Creek  Railroad  Arch,  British  Columbia 247 

223  Panther  Hollow  Bridge,  Pittsburgh 249 

224  Lincoln  Park  Arch-Cantilever,  Chicago,  111 251 

225  Coblenz  Arch  Bridge 253 

226  Alexander  III  Arch  at  Paris 255 

227  Worms    Highway    Bridge 257 

228  Bonn  Bridge  over  the  Rhine 259 

229  Duesseldorf  Bridge  over  the  Rhine 261 

230  Mainz  Bridge 263 

231  Kornhaus  Bridge  over  the  Aar  at  Berne 265 

SUSPENSION    BRIDGES 

232  The  Tower  Bridge,  London 267 

233  Conway  Suspension  Bridge,  England 269 

234  Budapest  Suspension    271 

235  The  Brooklyn  Bridge 273 

236  Sister  Island  Bridge,  Niagara 275 

CANTILEVER    BRIDGES 

237  Bridge  over  the  Hudson  at  Poughkeepsie,  N.  Y 277 

238  Red   Rock   Cantilever,    California 279 

239  The  Forth   Bridge,  Scotland 281 

240  Blackwell's  Island  or  Queensborough  Bridge 283 

LATTICE    TRUSS    BRIDGES 

24 1  Cologne   Railroad   Bridge 285 

242  Kehl  Bridge  over  the  Rhine 287 


INTRODUCTION 

BY  THOMAS   HASTINGS 

Among  all  the  varied  problems  of  construction  which  pre- 
sent themselves  to  human  ingenuity,  it  may  be  said  that  the 
bridge  most  influences  the  landscape  or  transforms  the  general 
character  of  a  city.  From  a  rustic  bridge  which  crosses  the 
brook,  lending  interest  to  the  woodland  scenery,  to  the  impres- 
sive construction  which  spans  the  mighty  river  without  interrupt- 
ing its  circulation,  whatever  may  be  its  purpose,  there  is  nothing 
human  which  may  add  more  to  the  beauty  of  a  landscape  or 
may  so  seriously  detract  from  it. 

Man  more  than  any  other  animal  has  always  been  migra- 
tory, penetrating  the  most  distant  regions,  and  to  this  end  he 
encircles  the  world  with  railroads,  pierces  the  mountains  with 
tunnels,  or  crosses  the  intervening  valleys  with  bridges  or  roads, 
giving  a  human  interest  to  nature  which,  in  its  primeval  con- 
dition, it  never  had.  There  is  no  more  lasting  or  permanent 
construction  than  that  of  the  bridge,  because  it  does  not  give 
way  to  the  changing  conditions  of  the  country,  or  to  the  growth 
and  development  of  the  city,  as  does  almost  any  other  archi- 
tectural structure.  It  is  therefore  evident  that  the  most  serious 
thought  should  be  given  to  the  character  and  design  of  such 
lasting  monuments. 

New  York  is  destined  to  have  more  bridges  of  colossal 
size  than  perhaps  any  other  great  city  of  the  world.  The  geo- 
graphical conditions  which  are  most  natural,  almost  like  those  of 
Venice,  isolate  the  city  on  an  island,  and  this  island  is  becoming 
more  and  more  overcrowded.  The  large  bodies  of  water  in  the 
immediate  neighborhood  of  the  metropolis  impose  varied  con- 
ditions upon  the  bridge  builder,  which  will  for  many  genera- 
tions to  come  bring  about  wonderful  developments  in  this  rela- 

1 


2  ARTISTIC  BRIDGE  DESIGN 

tion;  and  let  us  hope  that  these  great  bridges  will  make  the 
city  more  beautiful.  If  only  municipal  authorities  continue  to 
take  the  intelligent  interest  which  some  administrations  have 
manifested,  this  hope  may  be  realized.  It  would  be  difficult 
to  picture  how  beautiful  the  future  city  might  become  when 
in  time  these  bridges  make  their  impress  upon  the  many  miles 
of  water  front.  We  have  indeed  made  too  little  of  these 
natural  conditions  and  have  too  seldom  realized  how  much  the 
large  bodies  of  water — the  Sound,  the  Ocean  and  the  Rivers — 
mean  to  the  inhabitants  of  the  city,  not  only  for  purposes  of 
navigation  and  pleasure,  but  also  for  comfort  and  beauty. 
These  waters,  whose  tides  twice  a  day  bathe  our  shores,  mean 
more  to  us  than  we  can  realize,  and  to  appreciate  this  one  need 
only  to  visit  some  western  inland  town  to  feel  a  real  longing  for 
a  coast  environment. 

New  York  has  grown  too  large  for  Manhattan  Island,  and 
it  must  reach  out  and  over  the  waters  as  well  as  under  them. 
Our  highways  must  be  extended,  giving  most  interesting  prob- 
lems to  the  engineer  and  the  architect  for  many  generations  to 
come.  Let  us  hope  that  the  authorities  who  are  doing  so  much 
in  this  direction  will  some  day  force  the  railroads  to  have  more 
respect  for  private  property  instead  of  destroying,  as  is  so  often 
done,  the  entire  appearance  of  those  portions  of  the  towns  they 
pass  through,  seeing  only  the  commercial  side  or  how  m'uch 
money  can  be  drained  from  an  ever  patient  but  constantly 
moving  and  growing  population.  It  is  pitiable  indeed  to  note 
how  often,  especially  in  smaller  cities,  the  railroads  build  walls 
through  the  heart  or  center  of  a  town,  and  make  them  none  too 
good  for  mere  cellar  construction  with  ugly  guard  rails  of  pipe, 
without  the  slightest  consideration  of  the  feelings  of  the  prop- 
erty owners.  When  one  considers  the  enormous  cost  of  hun- 
dreds of  miles  of  railroads  from  place  to  place,  it  is  apparent 
how  comparatively  small  w^ould  be  the  increased  expenditure 
if  some  thought  were  given  to  making  such  constructions  in 
some  way  add  to  the  character  of  any  railroad  town. 

Since  the  recent  manufacture  of  wrought  iron  and  steel  in 


INTRODUCTION  3 

large  quantities  these  metals  have  in  a  great  measure  taken  the 
place  of  the  use  of  stone  or  wood  in  bridge  construction;  this 
has  had  a  very  great  influence  upon  architectural  development 
of  bridges.  The  influence  was  most  generally  felt  in  the  build- 
ing of  railroads  in  the  first  part  of  the  nineteenth  century.  There 
is  on  record,  however,  a  design  made  by  Thomas  Paine,  the 
author,  for  an  iron  bridge  in  the  year  1  786.  It  was  a  segmental 
arch  and  this  design  has  formed  the  basis  of  many  cast  iron 
arched  bridges  since  built.  The  model  for  this  bridge  was 
placed  on  exhibition  in  the  house  of  Benjamin  Franklin  in 
Philadelphia,  and  was  afterwards  sent  to  Paris,  where  it  was 
exhibited  at  the  Academy  of  Sciences. 

It  was  not  until  1840  that  any  great  iron  bridges  were 
built  in  this  country,  excepting  suspension  bridges,  where  iron 
links  were  used  in  the  cables  and  suspenders,  the  floors  being 
of  wood.  To  realize  the  great  influence  railroads  have  had 
upon  bridge  building,  we  must  consider  the  fact  that  prior  to 
1860  the  bridges  for  the  railroads  were  generally  designed 
by  the  railroad  engineers  and  executed  in  the  shops  of  the  rail- 
road companies.  This  made  an  emergency  demand,  and 
naturally  little  thought  was  given  to  aesthetics  or  to  the  per- 
manent character  of  such  constructions.  Later  the  railroads 
gave  the  building  of  these  bridges  to  construction  companies 
who  furnished  both  designs  and  bids  at  the  same  time,  and  it 
is  only  in  recent  years  that  the  engineers  in  this  class  of  work 
have  emerged  from  these  construction  companies  to  enter 
into  the  general  practice  of  this  profession.  In  designing 
bridges  and  writing  specifications  their  designs  were  to  become 
the  property  of  the  railroad  companies,  so  that  they  might 
obtain  competitive  bids  from  different  contractors. 

It  is  unfortunate  that  many,  though  by  no  means  all,  of  our 
highway  bridges  have  been  designed  by  engineers  who  have 
obtained  their  education  through  these  channels,  so  it  is  not  sur- 
prising that  there  has  been  a  marked  disregard  for  the  archi- 
tect and  his  work.  Unquestionably  until  modern  times,  most 
engineers  knew  more  about  architecture  than  they  do  today. 


4  ARTISTIC  BRIDGE  DESIGN 

as  also  did  architects  know  more  about  engineering,  but  with 
this  modern  tendency  of  differentiation  and  with  the  multitude 
of  complicated  problems  brought  about  by  iron  construction, 
there  must  be  more  collaboration  between  engineer  and  archi- 
tect in  order  to  produce  better  results  from  the  practical,  as 
well  as  from  the  artistic  point  of  view.  This  would,  indeed, 
be  an  advantage  not  only  in  that  it  would  make  the  bridge 
more  beautiful,  but  there  would  be  an  economy  of  time  and 
money  if  the  engmeer  and  architect  would  unite  in  the  design. 
From  the  first  they  would  work  hand  in  hand  to  scheme  the 
bridge,  instead  of  the  architects  being  called  in  at  the  last 
moment,  as  is  so  often  done,  merely  to  design  lamp  posts, 
balustrades  and  other  minor  details.  Planning  and  designing 
together,  the  architect  and  engineer  would  produce  most  satis- 
factory results.  In  matters  of  construction,  the  architect  mainly 
sees  the  qualitative  side  of  things,  while  the  engineer  s&es  the 
quantitative  side.  A  thing  builds  well  that  looks  well  and 
that  follows  the  laws  of  architectural  proportion  and  is  un- 
questionably more  economical.  Alas,  a  strange  sense  is  that 
sense  of  beauty  whose  absence  is  as  often  wanting  in  human 
character  as  is  the  sense  of  humor,  and  the  man  is  as  uncon- 
scious of  this  shortcoming  in  the  one  case  as  in  the  other.  He 
sometimes  even  seems  to  have  a  sort  of  disdain  for  any  thought 
of  the  beautiful,  and  the  deplorable  mistakes  he  makes  because 
of  this  fact  are  as  incurable  and  as  incorrigible  as  are  hereditary 
maladies.  He  shows  a  total  lack  of  respect  for  precedents,  or 
the  things  which  have  been  done  in  the  past.  He  little  realizes 
that  in  the  history  of  civilization  most  things  have  been  destroyed 
or  taken  down  which  were  only  practical.  I  really  believe 
that  in  our  conduct  of  life  even  a  moral  law  would  not  be 
adhered  to  unless  it  were  in  some  way  and  somehow  beautifully 
expressed. 

Leaving  the  architect  out  altogether  in  the  scheming  of 
a  bridge  is  as  though  he  were  to  be  left  out  in  the  designing  of 
tall  buildings,  because  so-called  skeleton  construction  has  come 
into  the  building  practice.     Such  tall  buildings  are  bad  enough 


INTRODUCTION  5 

as  it  is,  but  they  would  not  be  endurable  if  there  were  to  be 
an  exhibition  in  our  public  streets  of  their  unclothed  and 
unadorned  skeletons. 

There  is  great  hope  for  the  future  development  of  bridges 
in  that  there  seems  to  be  a  tendency  among  financiers  more 
closely  to  consider  the  question  of  maintenance  as  related  to 
original  cost  in  large  construction  enterprises,  and  this  will 
unquestionably  induce  them  to  build  more  largely  of  stone  and 
brick  than  has  been  the  case  until  this  generation.  In  fact,  it 
is  already  the  policy  of  the  Pennsylvania  Railroad  to  build 
stone  bridges  wherever  practicable.  It  means  much  for  art. 
To  everything  there  is  a  season,  and  a  time  for  every  purpose 
under  the  heavens.  ^_-. 

In  the  construction  of  stone  bridges  the  Romans  were  the 
first  great  builders.  Bridge  building  was,  in  fact,  one  of  the 
most  interesting  problems  they  had  to  solve.  In  architecture 
and  construction  they  were  indeed  a  most  original  and  artistic 
people;  too  little  appreciated  and  studied  by  modern  Anglo- 
Saxons.  They  were  the  forerunners  of  our  present  construc- 
tors. Until  their  time  the  Greeks  had  reached  that  measure  of 
perfection  now  so  much  considered,  and  theirs  was  the  culmina- 
tion of  the  slow  artistic  development  through  the  ages.  The 
Romans,  however,  had  presented  to  them  untried  problems  to  be 
solved  which  called  for  new  methods  of  construction,  and  of 
these  the  bridge  or  aqueduct  was  one  of  the  most  interesting. 
They  were  practically  the  first  people  to  use  the  principle  of  the 
arch  and  voussoir  construction.  The  use  of  the  arch  principle, 
while  sometimes  attributed  to  the  Chinese,  was  practically 
unknown  to  the  ancients  of  the  Western  civilization  until  the 
Roman  conquest.  It  has  been  contended  that  the  idea  of  the 
arch  principle  was  first  evolved  by  the  Etruscans.  If  this  is 
true,  it  is  indeed  coming  near  to  Rome. 

Such  wonderful  bridges  as  the  one  built  by  Caesar  Augus-         f 
tus  at  Rimini  or  the  Pont  du  Gard,  the  great  aqueduct  situated 
about  twenty  miles  from  Nimes,  built  across  the  river  Gard,  and 
attributed  to  Agrippa;  the  bridge  of  St.  Augustus  at  Rome, 


6  ARTISTIC  BRIDGE  DESIGN 

started  by  Adrian,  and  many  others  too  numerous  to  mention 
have  scarcely  ever  been  surpassed.  There  seems  to  have  been  a 
period  between  this  time  and  the  twelfth  century  when  few 
bridges  of  importance  were  built,  and  it  was  between  the  years 
1  1  78  and  1  1 88  that  the  famous  bridge  of  St.  Benezet,  at 
Avignon,  was  built.  Several  other  beautiful  bridges  soon  fol- 
lowed, similar  to  it  in  construction.  Then  came  the  early 
Renaissance  bridges,  also  too  numerous  to  mention — the  old 
Pont  Neuf  being,  perhaps,  the  finest  in  Paris;  the  famous 
bridge  attributed  to  Ammanati,  the  architect,  in  the  sixteenth 
century,  at  Florence ;  also  the  largest  stone  bridge  ever  built  in 
the  world,  with  a  span  of  one  hundred  and  eighty-three  feet  and 
a  rise  of  sixty  feet  over  the  Allier  at  Vielle  Brioude,  France; 
or  the  bridge  at  Chester  over  the  Dee,  forty  feet  high  with  two 
hundred  feet  span. 

Finally,  we  come  to  modern  times  full  of  interesting  exam- 
ples too  innumerable  to  catalogue,  excepting,  perhaps,  a  few  in 
our  immediate  neighborhood.  The  bridges  around  New  York 
are  more  interesting  from  the  engineering  point  of  view  than 
from  the  artistic.  It  would  seem  almost  a  sacrilege  to  criticise 
the  old  Brooklyn  bridge,  either  from  the  architectural  or  the 
engineering  standpoint.  It  is  too  much  a  part  of  us  which  we 
have  learned  to  revere  rather  than  to  criticise ;  nor  will  I  criticise 
the  new  Williamsburg  bridge.  I  refrain  from  criticism  on  gen- 
eral principles,  because  I  believe  criticising  individual  work 
often  does  more  harm  than  good. 

When  we  were  asked  to  design  in  collaboration  with  the 
engineers,  the  new  Manhattan  bridge,  before  beginning  studies 
we  rode  in  an  automobile  over  the  Brooklyn  bridge,  returning 
by  way  of  the  Williamsburg  bridge.  We  were  much  impressed 
with  the  added  interest  in  the  Brooklyn  bridge,  due  to  the  fact 
that  the  towers  of  that  old  structure  were  of  stone  rather  than 
of  iron,  giving  more  color  and  variety  to  the  composition.  We 
felt  greatly  the  need  of  stone  above  the  roadbed  in  the  proposed 
Manhattan  bridge,  the  third  large  one  to  be  built  across  the 
East  river;  and  with  this  in  view  we  took  advantage  of  the 


INTRODUCTION  7 

great  masonry  anchorage  necessary  to  receive  the  four  cables 
pulling  each  at  about  the  rate  of  ten  millions  of  pounds.  We 
felt  that  the  masonry  should  be  indicated  above  the  roadbed, 
and  with  this  in  view  we  designed  a  colonnade,  forming  a  court- 
yard of  stone  as  large  as  a  city  block  and  one  hundred  and 
twenty-five  feet  above  the  water,  making  a  vivid  contrast  with 
the  necessary  forest  of  iron  work. 

A  much  mooted  question  in  the  newspapers  and  elsewhere 
was  whether  these  bridges  were  all  to  be  made  through  thor- 
oughfares, and  with  this  in  view,  we  were  asked  to  design  a 
station  at  the  entrance  to  the  old  Brooklyn  bridge.  An  interest- 
ing condition  confronted  us,  and  one  which  the  critics  of  this 
project  do  not  seem  to  understand.  We  were  asked  to  design 
this  station  in  such  a  way  that  it  should  meet  the  conditions  then 
existing,  and  at  the  same  time  to  so  build  that  it  would  be  pos- 
sible at  a  small  expense  to  adapt  it  to  new  conditions  in  case 
of  through  traffic.  In  this  case  such  a  station  would  not  be  a 
terminal,  but  a  stopping  place  on  the  way.  It  is  unfortunate 
that  this  fact  has  been  so  little  understood,  as  I  believe  it  would 
silence  much  opposition.  The  problem  as  presented  to  us  by 
the  Bridge  Department  was  in  other  ways  most  interesting.  It 
was  proposed  to  design  a  building  in  such  a  way  that  a  vista 
through  a  great  triumphal  entrance  arch,  showing  the  old  stone 
towers,  might  be  obtained  by  people  walking  on  Broadway  or 
in  the  City  Hall  Park.  Here  is  one  of  the  greatest  bridges 
in  the  world,  and  yet,  with  the  present  deplorable  and  unprac- 
tical entrance,  one  does  not  know  when  in  this  neighborhood 
that  the  bridge  exists  until  one  is  actually  launched  half  way 
out  on  its  roadbed. 

All  tramways  or  trains  on  the  level  of  the  roadbed  of  the 
bridge  would,  according  to  the  new  plan,  go  under  ground, 
and  those  that  are  elevated  would  remain  elevated  at  the 
entrance,  to  the  height  of  twenty-five  feet,  so  as  to  make  the 
desired  vista  possible.  This  at  the  same  time  would  be  a 
wonderful  relief  to  the  congestion  at  this  point,  because  the 
entire  ground  floor  would  be  free  and  open  for  circulation. 


8  ARTISTIC  BRIDGE  DESIGN 

while  the  waiting  rooms  or  stations  would  be  above  and  below. 
This  was  one  of  the  most  interesting  architectural  problems 
we  have  ever  had  to  study,  and  if  carried  out,  it  would  offer 
for  further  study  a  most  engaging  architectural  problem.  The 
development  of  a  great  city  is  an  evolution,  and  we  need  make 
no  effort  to  find  ways  to  beautify  the  city ;  they  exist  everywhere 
if  we  will  but  recognize  them  when  they  are  offered. 


CHAPTER  I 
Importance  of  Bridges 

The  condition  and  character  of  bridges,  roads  and  other 
public  utilities  have  been  measures  of  civilization  in  all  ages. 
The  homeless  savage  in  trackless  wilds  had  little  need  for 
bridges,  as  his  wants  were  few  and  achievements  small.  But 
as  civilization  dawned,  human  needs  increased  and  the  desire 
for  greater  comforts,  better  homes  and  surroundings  created 
a  need  for  transportation  and  communication.  The  bridge  of 
fallen  logs  or  swinging  vines  (Fig.  1  *)  gave  place  to  better  and 


Fig.   1 

more  commodious  ones,  over  which  loaded  animals  and  carts 
could  pass  with  safety.  With  the  further  advance  of  civiliza- 
tion and  the  extension  of  commerce,  heavier  and  better  bridges 
were  required,  until  the  coming  of  railroad  transportation  in 
the  nineteenth  century,  when  stronger  ones  were  erected  to 
carry  trains  of  cars  and  locomotives.  The  earliest  bridges, 
like  houses  and  other  structures,  were  for  utility  only,  and  little 
or  no  thought  was  given  to  their  adornment.  Primitive  races 
were  content  with  homes  which  merely  sheltered  them  from  the 
storm  and  with  rude  bridges  which  served  only  their  barest 
needs  (Fig.  2*),  but  succeeding  generations  produced  buildings 
in  which  utility  was  combined  with  art.  While  houses  have 
been  adorned  and  made  architecturally  attractive,  the  beautify- 

*  From  "History  of  Bridge  Engineering,"  by  H.  G.  Tyrrell. 

9 


10 


ARTISTIC  BRIDGE  DESIGN 


ing  of  bridges  has  not  advanced  in  proportion  to  other  arts. 
Many  cities  which  have  splendid  buildings,  streets  and  parks, 
are  disfigured  with  utilitarian  bridges,  wholly  void  of  art  and 
worthy  of  existence  only  in  remote  regions.  The  greatest  lack 
of  art  in  bridges  is  found  in  America  and  other  new  countries, 
where  the  need  of  rapid  construction  has  prevented  aesthetic 
treatment. 

rrade  of 


Fig.   2 


As  the  latter  part  of  the  nineteenth  century  was  an  era  in 
which  bridges  of  great  proportions  were  erected,  so  the  first 
part  of  the  tv/entieth  century  will  doubtless  witness  the  begin- 
ning and  development  of  bridge  architecture  in  America.  Prog- 
ress in  this  direction  is  strikingly  illustrated  in  the  city  of  New 
York.  Thirty  years  ago  the  Brooklyn  bridge  (Fig.  235)  was 
erected  as  a  great  utilitarian  structure  with  little  or  no  thought 
for  its  adornment,  but  on  some  of  the  later  bridge  designs  in 
that  city,  the  carrying  out  of  which  has  unfortunately  been 
prevented  by  other  interests,  a  great  amount  of  art  has  been 
displayed. 

Great  bridges  are  a  distinctive  feature  of  modern  cities 
and,  according  as  they  are  attractive  or  not,  they  influence  pub- 
lic estimation  of  the  place  in  which  they  are  located.  The 
beautiful  bridges  of  Paris,  Berlin  and  Budapest  are  of  enough 
interest  in  themselves  to  attract  travelers  to  those  cities,  and 
the  bridges  over  the  Rhine  are  among  the  principal  features  of 
the  region.  Progress  in  America  is  well  illustrated  by  compar- 
ing the  old  King's  and  Farmer's  bridges  at  New  York,  of  the 
seventeenth  and  eighteenth  centuries,  with  the  four  great  ones 
over  the  East  river  which  are  the  most  conspicuous  objects  in  the 
landscape. 


IMPORTANCE  OF  BRIDGES  11 

MAGNITUDE  OF  SUBJECT 

v^Since  the  middle  of  the  nineteenth  century  bridge  building 
has  developed  into  one  of  the  greatest  of  modern  enterprises.^ 
In  the  United  States  alone  there  are  about  80,000  metal  bridges 
with  an  aggregate  length  of  1 ,400  miles,  or  one  bridge  for  every 
three  miles  of  railroad.      In  addition  to  this  there  are  about 
200,000  wooden  trestles  with  an  aggregate  length  of  about 
3,000  miles.     The  largest  ones  are  those  over  the  great  conti- 
nental rivers  of  Europe,  Asia  and  America,  the  most  important 
being  in  America.     Metal  bridges  in  America  alone  are  valued 
at  $800,000,000,  and  the  building  of  them  has  given  employ- 
ment directly  or  indirectly  to  many  thousands  of  men.     Mines 
are  equipped  and  operated  to  produce  the  ore  and  coal,  rolling 
mills  to  make  the  finished  shapes  and  plates,  and  bridge  and 
structural  works  to  fabricate  the  parts.     Other  industries  are 
employed  in  making  machinery,  tools  and  supplies  for  the  mines, 
rolling  mills  and  shops,  and  still  others  are  engaged  in  supply- 
ing the  wants  and  equipment  of  those  who  manufacture  the 
tools.     A  large  amount  of  capital  is,  therefore,  invested  not 
only  in  the  bridges  themselves  but  also  in  the  mines,  mills  and 
shops  for  producing  them.     Shipping  them  gives  business  to 
railroad  and  steamship  lines,  and  the  work  of  erection  gives 
employment  to  many  workmen.    The  making  of  travelers,  false- 
work and  other  appliances  is  frequently  as  difficult  as  the  manu- 
facture of  the  bridges  themselves  and  their  erection  is  often  car- 
ried on  in  countries  remote  from  sources  of  supply.    Schools  and 
colleges  are  equipped  and  conducted  for  training  engineers, 
chemists  and  other  technical  men,  and  publishers  and  printers 
are  employed  in  supplying  technical  literature.      The  effect, 
therefore,  of  bridge  building,  like  other  great  enterprises,  is  felt 
throughout  the  whole  world  and  nearly  all  people  are  in  one 
way  or  another  benefited.    An  industry  involving  so  great  capi- 
tal investment  and  the  labor  of  so  many  persons  is  therefore 
deserving  of  the  most  careful  study.     If  the  design  is  faulty, 
the  money  invested  and  the  labor  spent,  both  directly  or  indi- 
rectly, in  allied  industries,  is  wasted.     This  is  well  illustrated  ii? 


12 


ARTISTIC  BRIDGE  DESIGN 


the  ill-fated  Quebec  bridge,  which  fell  before  completion,  and 
also  in  many  others  which  are  failures  in  other  ways.  Ugly 
bridges  in  beautiful  surroundings  are  artistically  unsatisfactory, 
and  those  which  must  too  often  be  renewed  are  failures  finan- 
cially because  of  the  selection  of  a  wrong  material  for  the  duties 
imposed  upon  them.  The  need  for  greater  attention  to  design 
is  therefore  evident,  as  upon  it  the  whole  success  or  failure  of  the 
structure  depends. 

No  project  is  now  too  great  for  investigation.  Designs  have 
been  made  for  a  bridge  twenty-one  miles  long,  to  cross  the  Eng- 
lish Channel  (Fig.  3),  and  though  financially  impractical,  one 


Fig.   3 


of  America's  leading  engineers  has  declared  that  one  on  float- 
ing piers  could  be  built  across  the  Atlantic,  giving  railroad  com- 
munication between  the  two  continents.  As  far  as  engineering  is 
concerned,  almost  any  project  is  possible  if  enough  money  is 
available. 

Practical  span  limits  in  steel  have  now  been  reached,  but 
the  investigations  of  metallurgists  and  chemists  may  lead  to  the 
production  of  new  building  material  by  the  use  of  which  greater 
lengths  will  be  possible.  Long  spans  are  in  many  cases  an  evi- 
dent advantage.  The  busy  water  courses  of  large  cities  like 
London  and  Paris  are  most  useful  when  unobstructed  with  piers» 


IMPORTANCE  OF  BRIDGES 


13 


and  since  larger  spans  have  become  possible,  many  old  bridges 
with  shorter  ones  have  been  replaced  by  others  with  longer  open- 
ings. The  present  London  bridge  with  four  river  piers  replaced 
one  (Fig.  4)  which  had  nineteen  piers,  obstructing  two-thirds 
of  the  river  channel,  and  the  Seine  at  Paris  and  Tiber  at  Rome 
are  now  crossed  with  single  spans.    The  bridges  of  New  York 


TfT^^' 


Fia 


and  some  other  cities  are  far  more  conspicuous,  especially  from 
the  river,  than  all  their  great  buildings,  which  have  cost  untold 
millions. 


RELATION  OF  BRIDGES  TO  HUMAN  PROGRESS 

Rivers  have  often  been  a  dividing  line  between  races  and 
nations.  Before  the  days  of  bridges,  each  tribe  was  content 
with  the  products  of  its  own  territory,  but  as  a  desire  grew  to 
enjoy  the  good  things  of  adjoining  countries,  the  rivers  and 
territorial  boundaries  were  crossed,  and  adjoining  tribes  ex- 
changed their  commodities  with  each  other.  Such  intercommu- 
nication, from  which  the  benefit  was  great  and  evident,  naturally 


14 


ARTISTIC  BRIDGE  DESIGN 


developed  and  increased.  The  founding  and  building  of 
empires  has  always  been  dependent  on  roads  and  bridges.  The 
Romans  saw  that  the  requisites  for  a  great  nation  were  a  fertile 
soil,  natural  resources  and  abundant  means  of  transportation, 
and  the  excellence  of  the  Roman  roads  has  scarcely  been  sur- 
passed.   Their  roads  and  bridges  (Fig.  5*)  have  endured  for 


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fefjUT^-rL 

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more  than  twenty  centuries,  and  are  used  by  the  present  gener- 
ations. Without  roads,  the  settlement  of  a  country  is  impossi- 
ble. In  the  opening  up  and  development  of  the  United  States, 
Canada,  Africa  and  Australia,  an  extensive  policy  of  road  con- 
struction has  been  carried  out,  often  at  the  expense  of  the 
national  government,  for  when  roads  are  built,  the  settlement 
of  the  country  and  the  growth  of  towns  and  cities  is  assured. 

The  building  of  roads  and  bridges  has  therefore  been  the 
greatest  factor  in  the  development  of  nations  and  empires,  and 
the  condition  of  these  utilities  has  always  been  a  measure  of 
their  civilization  and  greatness.  In  the  middle  of  the  eighteenth 
century,  France  realized  its  need,  and  created  a  Department 
of  Bridges  and  Highways  in  the  national  government,  and 
fifty  years  later  England  constructed  more  than  a  thousand 

es  of  highway  under  the  able  direction  of  Thomas  Telford. 


mi 


*  From  Concrete  Kridges  and  Culverts.     By  H.  G.  Tyrrell. 


IMPORTANCE  OF  BRIDGES  15 

Few  works  are  of  greater  service  to  mankind.  Commerce  is 
created  and  the  products  of  civilization  can  be  distributed  for 
the  benefit  of  all.  Workers  in  crowded  metropoHtan  quarters 
are  permitted  to  live  in  rural  or  suburban  districts  amid  more 
healthful  surroundings;  sickness  is  avoided  and  the  lives  of 
workmen  and  their  families  are  lengthened  and  made  more 
secure.  The  building  of  highways  and  railroads  opens  up  new 
tracts  and  increases  land  values  enough  many  times  to  repay 
their  cost. 


"^-*---' 


CHAPTER  II 
Reasons  for  Artistic  Bridges 

Bridges  are  frequently  the  most  conspicuous  objects  in  the 
landscape.  Unlike  buildings  in  crowded  city  squares  which 
are  partly  concealed  by  their  surroundings,  a  bridge  can  often 
be  seen  for  a  great  distance.  The  greatest  injustice  to  public 
taste  or  feeling  is  the  building  of  an  ugly  bridge,  for  the  most 
prominent  and  useful  structures  should  be  the  most  beautiful; 
and  yet  the  reverse  has  been  the  custom,  particularly  in  Amer- 
ica. City  halls,  postoffices,  and  other  public  buildings  which 
are  less  prominent,  and  of  much  less  use  or  value,  have  been 
adorned  with  art,  and  bridges  have  been  neglected.  Cities 
have  failed  to  realize  that  it  is  as  important  to  ornament  their 
bridges  as  their  city  halls  or  court  houses.  Consistency  is  lack- 
ing even  to  a  greater  extent  on  railroads  than  on  municipal 
buildings,  for  great  terminal  depots  are  erected  in  the  cities, 
and  smaller  but  architecturally  beautiful  ones  at  suburban  sta- 
tions, while  adjoining  bridges  which  are  often  more  conspicuous 
than  the  stations  are  left  utterly  void  of  art.  This  condition  is 
too  evident  to  need  special  reference.  Often  within  a  few 
blocks  of  a  great  terminal  station,  common  truss  bridges 
(Fig.  6)   may  be  seen  spanning  the  streets,  suitable  only  for 


Fig. 


remote  or  rural  districts  where  they  would  be  seldom  or  never 
seen.  The  custom  in  America  has  already  begun  to  change, 
for  all  structures,  including  bridges  and  stations,  were  formerly 
designed  by  railroad  engineers,  without  architectural  assistance, 
and  had  little  or  no  pretention  to  art.     But  now  both  metropol- 

16 


REASONS  FOR  ARTISTIC  BRIDGES  17 

itan  and  suburban  stations  are  the  work  of  architects  or  the 
combined  work  of  architects  and  engineers,  and  there  is  no 
doubt  that  bridges  will  soon  be  similarly  treated.  It  will  be 
impossible  much  longer  to  tolerate  the  discord  or  lack  of  con- 
sistency and  harmony  between  the  beautiful  station  and  the 
purely  utilitarian  bridge  adjoining  it.  Whichever  one  is  the 
most  conspicuous  is  most  deserving  of  decoration,  and  finials 
or  other  decorative  features  are  quite  as  appropriate  on  a  bridge 
as  the  spires  and  towers  on  the  adjacent  building.  If  the  ap- 
pearance of  a  bridge  is  of  no  importance,  the  buildings  should 
then  be  made  to  correspond,  and  be  similarly  devoid  of  art. 

Another  reason  for  building  ornamental  bridges  is  that  their 
form  and  location  are  frequently  inviting  for  artistic  treatment. 
The  curved  lines  of  the  arch  and  suspension  are  in  themselves 
attractive,  and  may  be  beautified  without  much  effort.  It  is 
easy,  therefore,  to  make  a  bridge  one  of  the  most  beautiful  and 
interesting  objects  in  the  landscape.  No  structure  more  clearly 
shows  its  object  and  use,  and  the  opportunity  is  therefore  offered 
for  truthful  construction,  a  prime  requisite  for  good  design. 
Bridges,  and  especially  high  ones,  are  naturally  impressive,  and 
no  objects  in  the  landscape  are  longer  remembered.  Return- 
ing travelers  often  retain  the  picture  of  a  bridge  in  mind  after 
monumental  buildings  have  been  forgotten. 

Bridges  should  be  made  beautiful  because  people  delight 
to  congregate  and  loiter  upon  them,  particularly  in  the  summer 
time.  For  this  reason  a  bridge  is  especially  suitable  for  a  memo- 
rial, as  it  can  be  appreciated  and  admired  during  leisure  hours. 
Among  the  memorial  bridges  of  America  are  the  Witmer 
bridge,  near  Lancaster,  Pa.,  erected  by  Mr.  and  Mrs.  Witmer 
in  1800;  the  memorial  bridge  at  Milford,  Conn.;  one  at 
Hartford,  Conn.  (Fig.  14),  and  the  Schell  memorial  at 
Northampton,  Mass.  Large  ones  have  been  proposed  at 
Washington  and  New  York  (Figs.  217-220). 

Bridges  should  be  beautiful  because  the  presence  of  orna- 
mental structures  enhances  the  value  of  the  surrounding  prop- 
erty.    Those  entrusted  with  the  expenditure  of  public  money 


18 


ARTISTIC  BRIDGE  DESIGN 


should  realize  the  economy  of  building  artistically  in  and 
around  large  cities  and  centers  of  population,  for  money  thus 
spent  is  frequently  a  good  investment.  Fine  bridges  give  a  dis- 
tinctive feature  to  a  city.  Those  in  France  and  Germany  and 
some  few  in  America  show^  possibilities  in  artistic  metal  con- 
struction. The  thirty-two  bridges  over  the  Seine  at  Paris  are 
in  most  cases  models  of  elegance,  standing  out  in  sharp  and 


Fig.  7 


charming  contrast  to  those  in  some  American  cities,  like  Chi- 
cago. But  the  time  for  better  ones  in  America  seems  to  be  at 
hand.  Bridges  devoid  of  art  (Fig.  7),  which  were  excusable 
in  the  early  days  of  the  republic,  should  no  longer  be  tolerated. 
The  wealth  and  commerce  of  America  have  so  increased  that 
the  uncouth  forms  of  past  generations  are  no  longer  permissible 
as  representative  works  of  a  great  nation. 


CHAPTER  III 
Standards  of  Art  in  Bridges 

The  bridges  and  structures  erected  by  a  people  or  nation 
reveal  their  degree  of  aesthetic  taste  and  are  a  measure  of  their 
culture  and  civilization.  Bridges  should  be  strong  enough  to 
last,  and  beautiful  enough  to  be  worth  preserving.  Some  old 
Roman,  Chinese  and  Persian  stone  bridges  display  an  amount 
of  art  which  has  hardly  been  surpassed  in  modern  times. 

In  adopting  standards  of  art  for  bridges,  it  must  be  borne 
in  mind  that  these  structures  should  be  pleasing  not  only  to 
the  engineer  and  architect,  but  also  to  people  who  may  have 
no  more  than  ordinary  appreciation  of  art.  Taste  depends 
largely  upon  environment  from  infancy.  Those  who  live  in 
primitive  and  rustic  surroundings  have  not  the  aesthetic  sense 
so  highly  developed  as  their  more  favored  brothers  in  the  vicin- 
ity of  educational  and  cultured  centers,  and  yet  all  have  some 
appreciation  for  objects  of  beauty.  The  architectural  stand- 
ards of  other  ages  cannot  always  be  applied,  for  modern  con- 
ditions and  building  materials  are  different,  and  instead  of  ad- 
hering to  the  art  standards  of  the  ancients,  a  better  way  is 
to  do  as  they  did,  and  make  the  best  construction  that  condi- 
tions will  permit.  Standards  in  architecture  have  been  estab- 
lished for  centuries,  and  buildings  which  harmonize  with  them 
are  satisfying.  These  standards  may  and  frequently  are  ap- 
plied to  stone  bridges  with  excellent  results,  but  different  ones 
are  needed  for  concrete  and  metal.  Steel  bridges  have  been  the 
subject  of  much  unjust  criticism,  due  to  comparison  with  wrong 
standards.  Framed  trusses  are  so  different  from  stone  arches 
that  they  must  be  judged  differently,  and  as  the  public  learns 
their  meaning  and  the  difficulty  of  designing  them,  they  will  be 
more  appreciated.  ^ 

19 


20  ARTISTIC  BRIDGE  DESIGN 

The  best  standards  are  those  suggested  by  nature.  Ob- 
jects in  a  natural  landscape  harmonize  with  each  other.  The 
trunks  of  trees  taper  towards  the  top  as  less  strength  is  required, 
and  at  the  base  the  roots  spread  out  and  anchor  them  to  the 
ground.  Limbs  branch  out  on  all  sides  to  give  them  poise. 
Limbs  and  branches,  which  are  the  framing,  are  covered  with 
beautiful  foliage,  and  the  earth  is  covered  with  green  and  flow- 
ers. Mountains  slope  upward  from  their  bases  and  have  the 
greatest  area  where  it  is  needed,  at  the  bottom.  The  purpose 
of  natural  objects  is  generally  evident  and  rarely  concealed. 
The  sun  furnishes  light ;  the  rivers,  water ;  and  the  trees,  shade 
in  summer.  Curves  are  the  lines  of  nature,  and  ornament  is 
displayed  where  it  can  be  seen  and  appreciated.  As  a  general 
rule,  therefore,  when  structures  conform  with  nature,  they  are 
pleasing,  and  they  displease  when  they  lack  such  harmony  or 
contradict  it.  In  nature  we  find  the  branches  of  certain  trees 
and  shrubs  are  hollow,  as  also  are  the  stalks  of  corn  and  cane, 
and  the  stems  which  bear  the  heads  of  wheat  and  other  grain. 
The  engineer  has  therefore  selected  hollow  members  as  an 
effective  structural  form,  and  they  may  be  found  on  many  im- 
portant bridges  such  as  that  over  the  Firth  of  Forth  in  Scotland. 
Bridges  are  therefore  considered  beautiful  when  they  fulfill 
the  following  requirements: 

1 .  Conformity  with  environment. 

2.  Economic  use  of  material. 

3.  Exhibition  of  purpose  and  construction. 

4.  Pleasmg  outline  and  proportions. 

5.  Appropriate  but  limited  use  of  ornament. 

1 .  A  bridge  must  conform  with  its  surroundings  and  envi- 
ronment. In  a  wild  mountain  gorge  large  spans  of  bold  design 
without  applied  ornament  are  the  most  appropriate,  while  In 
wooded  parks  a  rustic  bridge  (Figs.  161-162*)  fits  better  Into 
the  landscape.  In  a  city  park  or  public  square,  where  finet 
ornament  is  in  evidence,  a  bridge  with  fine  detail,  smooth  face 

*  IT,   O.   TyiTPll,   in  Ampvican  Architect,  Aug.  24,  1901. 


STANDARDS  OF  ART  IN  BRIDGES 


21 


and  smaller  ornament  is  preferable  (Fig.  182).  The  setting 
or  surroundings  greatly  affect  its  appearance.  A  bridge  cross- 
ing a  river  at  a  great  height  (Fig.  8)  is  naturally  imposing, 
while  the  same  one  at  a  low  level  would  lack  much  of  its  charm. 
Those  which  are  exposed  to  the  river  view  are  seen  and  more 
appreciated  than  others  amid  sordid  surroundings  partly  hidden 
by  adjoining  objects. 

2.  Economic  use  of  material  is  another  standard  of  excel- 
lence. Beauty  exists  in  every  structure  which  is  designed 
according  to  the  principles  of  economy,  with  the  greatest  sim- 
plicity, the  fewest  members  and  the  most  pleasing  outline  con- 
sistent with  construction.     Requirements  of  utility  may  neces- 


Fig.  8 


sitate  certain  forms  unfamiliar  to  the  public  mind,  but  as  the 
purpose  and  design  of  bridges  are  better  understood,  these 
forms  will  be  more  appreciated.  The  principle  is  an  essential 
of  design  and  must  overrule  public  preference.  Strength  and 
economy  are  the  controlling  motives,  but  art,  though  second- 
ary, must  not  be  neglected. 

3.  The  purpose  of  the  bridge  should  be  plainly  evident, 
and  generally  the  construction  should  be  revealed.  Expressive- 
ness, to  many  people,  is  the  chief  source  of  beauty.     Strength 


22 


ARTISTIC  BRIDGE  DESIGN 


and  boldness  should  predominate.  Imitation  or  deception 
must  be  avoided  and  the  design  truthfully  shown.  If  spandrels 
of  masonry  bridges  are  hollow  they  should  appear  open  on 
the  face  rather  than  enclosed  with  curtain  walls.  A  girder 
should  not  be  formed  to  imitate  an  arch,  and  false  members  in 
trusses  should  be  avoided  or  used  with  caution. 

4.  A  bridge  is  beautiful  if  its  primary  form  or  outline 
and  its  relative  proportions  are  well  and  properly  chosen.  A 
spectator  is  more  impressed  by  the  general  form  than  by  an 
endless  wealth  of  detail,  and  when  the  outline  is  correct,  little 
detail  ornament  is  needed.  The  proportions  must  satisfy  the 
eye  and  the  aesthetic  feeling,  and  have  optical  harmony.  Pro- 
jections and  corresponding  heavy  shadows  on  masonry  give  an 
appearance  of  strength  and  introduce  contrast,  which  is  one  of 
the  elements  of  beauty.     Voids  and  solids  should  be  arranged 


Fia 


in  satisfying  proportion.  The  lines  of  the  arch  (Fig.  9)  and 
suspension  are  in  themselves  enough  to  give  a  fine  effect.  Arches 
must  be  perfect  curves  and  false  ellipses  with  less  than  nine  or 
eleven  centers  should  be  avoided.  Curved  lines  are  more  beau- 
tiful than  straight  ones,  but  the  outline  selected  must  be  con- 
sistent with  economy.  Small  bridges  should  have  finer  outlines 
and  a  larger  amount  of  detail  than  greater  ones. 

5.  As  the  bare  skeleton  of  a  tree  or  animal  is  beautified 
with  foliage  or  covering,  so  the  framing  and  construction  of  a 
bridge  should  be  ornamented.  The  relative  weight  of  timber 
and  leaves  on  a  tree  is  suggestive  of  the  extent  to  which  orna- 
ment is  permissible  on  structures.  Superfluous  decoration  has 
a  minifying  effect  and  is  sometimes  ridiculous.  The  bridge 
at  Callowhill  street,   Philadelphia,   originally   faced  on   each 


STANDARDS  OF  ART  IN  BRIDGES  23 

side  with  sheet  metal  arcades,  was  an  illustration  of  excessive 
ornamentation.  A  somewhat  similar  design,  made  in  1 867  by 
George  A.  Parker  for  a  bridge  at  Havre  de  Grace,  showed  the 
proposed  structure  covered  on  the  outside  with  ornamental  iron. 
It  was  illustrated  at  the  time  in  the  Journal  of  the  Franklin 
Institution,  and  was  considered  a  fine  piece  of  work.  The  cover- 
ing met  with  so  much  disapproval  that  it  was  soon  removed. 
The  beautiful  Bonn  bridge  (Figs.  68-228)  over  the  Rhine — 
one  of  the  finest  in  Europe — has  elaborate  detail  ornament  on 
the  metal  portals,  which  would  be  inappropriate  elsewhere, 
though  perhaps  suitable  in  its  place.  Ornament  is  not  archi- 
tecture, and  a  bridge  of  beautiful  outline  may  easily  be  spoiled 
with  an  excessive  amount  of  detail. 


CHAPTER  IV 
Causes  for  Lack  of  Art 

No  objects  in  America  more  greatly  mar  the  landscape  than 
the  bridges,  and  none  in  Europe  are  more  attractive.  In  and 
about  American  cities  ordinary  truss  bridges  are  common,  and 
many  of  the  most  conspicuous  ones  are  artistically  worth- 
less. Adjoining  the  beautiful  Back  Bay  Railway  Station  in 
Boston,  within  a  few  blocks  of  Copley  Square  and  the  finest 
residential  district,  stood  an  ugly  truss  carrying  Dartmouth 
street  over  the  railway  tracks.  The  contrast  was  striking  as 
the  traveler  emerged  from  the  handsome  building  on  his  way 
to  the  finest  portion  of  the  city,  to  be  at  once  confronted  with 
this  uncouth  structure,  suitable  only  for  some  remote  factory 
district  or  region.  The  reasons  for  lack  of  beauty  in  American 
bridges  are  as  follows: 

1 .  Indifference  of  engineers  and  their  lack  of  artistic 
training. 

2.  Competition  and  commercialism,  resulting  in  use 
of  contractors'  plans. 

3.  Lack  of  cooperation  from  architects. 

4.  Absence  of  art  standards  for  metal  bridges. 

5.  Haste  in  construction. 

6.  Railroad  bridges  used  as  prototypes  for  others. 

7.  Legal  and  financial  hindrances. 

8.  Inadequate  material. 

9.  Unsuitable  or  unsymmetrical  location. 

1 0.     Absence  of  state  or  municipal  supervision. 

1 .  Little  or  no  literature  on  artistic  bridge  design  was  avail- 
able for  engineers  and  no  instruction  was  given  on  the  subject  in 
American   engineering   schools.      In   France,   conditions  were 

24 


CAUSES  FOR  LACK  OF  ART  25 

quite  different,  for  there  a  teacher  of  architecture  is  associated 
with  these  institutions.  Engineers  in  America  were  therefore 
ignorant  of  the  principles  of  aesthetics,  or  had  given  no  time  or 
thought  to  the  cultivation  of  their  taste  in  this  direction.  Whe.re 
there  is  no  desire  for  artistic  production,  it  is  certain  that  none 
will  result.  Many  engineers  not  only  neglected  this  feature 
of  design,  but  actually  ridiculed  aesthetics,  gaining  for  them- 
selves the  title  of  "eminent  engineers  but  professional  vandals." 
Pleasing  outlines  were  discarded  and  preference  given  to  purely 
utilitarian  forms.  Their  only  object  has  been  to  design  bridges 
of  sufficient  capacity  and  strength,  and  accomplish  this  result 
with  the  least  expenditure  of  money.  Ugly  designs  were  often 
made  when  artistic  ones  would  have  cost  no  more.  After 
selecting  a  general  outline  that  was  absurdly  far  from  the  proper 
one,  many  engineers  would  then  compute  the  stresses  in  the 
selected  forms,  carrying  their  figures  out  to  decimals,  when  the 
primary  assumptions  might  never  be  realized  within  one  hun- 
dred per  cent  or  more.  In  reference  to  this  custom  of  fine 
proportioning,  when  writing  particularly  about  computations 
for  engine  loadings.  Professor  William  H.  Burr  says: 
"Nothing  is  to  be  gained  by  this  figment  of  ridiculous  refine- 
ment ;  in  fact,  much  is  to  be  gained  by  its  relegation  to  obscurity. 
A  solacing  memory  will  always  be  preserved  for  the  awe- 
inspiring  literature"  on  the  subject  "which  has  been  written  to 
show  what  splendid  mathematical  gymnastics  can  be  performed 
in  its  treatment.  But  it  can  be  confidently  asserted  that  no 
single  structure  has  ever  been  made  a  shade  better  for  its  pur- 
pose, or  more  creditable  in  its  design,  by  the  use  of  the  method." 
Another  critic  declares  that  "some  enginsers  exhibited  a  willful, 
and  most  engineers  a  careless,  indifference  for  design ;  for  after 
executing  some  especially  revolting  work,  painted  in  triumphal 
red,  they  exulted  over  the  disfigured  city  or  the  insulted  land- 
scape like  a  conquering  savage." 

2.  Commercialism  and  competition  are  responsible  to  a 
great  extent  for  a  lack  of  art  in  American  bridges,  for  as  a  gen- 
eral rule,  the  cheapest  bridge,  and  consequently  the  plainest 


26  ARTISTIC  BRIDGE  DESIGN 

one,  was  accepted,  and  ornamental  designs  at  greater  cost  were 
discarded.  These  designs  were  prepared  by  contractor's 
engineers,  whose  chief  and  often  only  motive  was  personal  gain. 
Under  these  conditions,  it  was  generally  useless  to  make  artistic 
designs,  and  engineers  became  accustomed  only  to  the  cheapest 
forms,  and  were  inexperienced  in  any  other. 

3.  Cooperation  of  architects  was  considered  unnecessary, 
and  none  was  given.  The  architect  knew  little  of  engineering, 
and  the  engineer  nothing  of  architecture,  each  finding  that  all 
his  time  and  energy  were  required  to  master  his  own  work. 
Railroad  terminals  and  depots  were  formerly  the  work  of 
engineers,  and  not  till  lately  has  the  aid  of  architects  been 
invoked  on  these  structures.  When  members  of  the  two  pro- 
fessions work  together  on  bridges  as  they  do  now  on  large 
buildings,  the  results  should  be  more  fortunate. 

4.  Another  reason  for  the  lack  of  art  was  that  no  stand- 
ards for  metal  bridges  were  available,  and  precedent  in  stone 
was  of  no  value.  Metal  was  declared  to  be  a  hard  material  to 
beautify,  and  until  recently  there  has  been  little  or  no  expe- 
rience in  this  direction.  Early  efforts  in  ornamental  wrought 
iron  bridges  in  America  were  a  failure,  and  some  in  Europe, 
including  the  Bonn  bridge  over  the  Rhine  (Fig.  228),  which 
is  graceful  in  almost  every  particular,  have  rather  unfortunate 
decorative  features. 

5.  Hasty  construction  is  perhaps  responsible  for  more  ugly 
bridges  than  any  other  cause.  New  countries  like  the  United 
States  of  America  and  Canada  were  opened  up  to  settlement, 
by  projecting  long  lines  of  railroad  across  the  continent.  As 
further  construction  was  dependent  on  the  completion  of 
bridges  over  which  work  trains  and  supplies  could  pass,  the 
greatest  possible  haste  was  necessary,  and  temporary  bridges 
and  timber  trestles  were  extensively  employed.  The  usual 
policy  has  been  to  complete  the  road  and  have  it  open  for 
travel  at  the  least  possible  first  cost.  This  haste  and  the 
desire  for  the  least  expense  has  resulted  in  the  general  adoption 
of  metal  trusses  with  parallel  chords  (Fig.   10),  which  were 


CAUSES  FOR  LACK  OF  ART 


27 


cheaply  made  and  quickly  put  together.  These  types  therefore 
became  the  prevailing  ones  and  were  erected  all  over  the  Amer- 
ican continent.  In  Europe,  conditions  were  different,  for  the 
railroads  there  were  constructed  through  thickly  settled  regions 
and  extensive  business  was  at  once  assured.  Under  these  condi- 
tions, temporary  and  low  cost  bridges  were  less  in  evidence,  and 
better  ones  were  made  during  the  first  construction. 

6.  The  American  railroad  truss  bridge,  which  was  the 
common  and  almost  only  form,  became  the  prototype  for  town 
and  city  bridges,  and  these  ugly  structures  may  now  be  found 


Fig.  10 


both  in  remote  regions  and  in  the  center  of  great  cities.  Smaller 
spans  are  usually  the  worst  appearing,  for  their  height  is  out 
of  proportion  to  their  length,  and  they  have  no  other  indication 
than  mill  and  factory  products.  In  bridges,  as  in  other  things, 
custom  governs  to  a  large  extent,  and  up  to  the  present  time  the 
prevailing  fashion  is  the  economical  though  unsightly  truss. 

7.  The  financial  limitation  or  necessity  for  low  first  cost 
of  railroad  bridges  was  equally  evident  in  towns  and  cities, 
where  the  lowest  tender  offered,  often  on  the  bidder's  own 
design,  was  usually  accepted.  A  common  explanation  of  un- 
sightly bridges  is  therefore  the  excuse  of  insufficient  funds  or 
appropriation.  The  plea  is  evidently  without  foundation,  for 
cities  which  spend  millions  on  their  public  buildings  could  better 
afford  to  beautify  their  bridges,  which  are  often  much  more 
conspicuous.  Legal  hindrances  may  also  interfere  with  the  erec- 
tion of  suitable  designs. 

8.  Suitable  material  for  ornamental  work  is  not  always 
at  hand,  but  this  need  not  prevent  the  adoption  of  artistic 
forms,  for  bridges,  even  of  the  rudest  character,  may  often  be 
beautified  without  adding  greatly  to  their  cost. 


28  ARTISTIC  BRIDGE  DESIGN 

9.  The  location  may  be  such  that  any  bridge  of  an  orna- 
mental character  would  be  out  of  place.  No  one  would  con- 
sider a  monumental  one  for  a  rural  district  where  it  would  be 
little  seen,  and  in  such  locations  ornamental  bridges  are  unsuit- 
able. The  site  also  affects  its  appearance,  for  if  the  surround- 
ings are  beautiful  the  bridge  will  be  more  attractive.  If  the  pro- 
file or  ground  contour  is  unsymmetrical,  it  is  more  difficult  to 
make  a  symmetrical  and  satisfactory  arrangement  of  spans. 

10.  The  absence  of  state  or  municipal  supervision  of 
bridges  permitted  the  acceptance  of  uncouth  designs  which 
might  have  been  prevented.  But  the  municipal  art  commis- 
sions, now  active  in  many  large  cities,  instead  of  promoting  art, 
have  often  hindered  it,  as  is  well  illustrated  in  New  York  by 
the  rejection  of  several  bridge  designs  of  unusual  merit,  and 
the  ultimate  abandonment  of  the  whole  projects.  State  com- 
missions are  fortunately  more  successful,  and  in  some  states 
bridge  designs  must  be  approved  by  the  commission  before 
construction  can  be  started. 


CHAPTER  V 

Special  Features  of  Bridges 

Bridges  have  had  many  uses  in  addition  to  forming  a  pas- 
sageway for  travel,  and  ancient  and  mediaeval  ones  were  fre- 
quently lined  on  either  side  with  shops,  or  used  as  a  gathering 
place  for  citizens.  Old  London  bridge  (A.  D.  1  1 11^  ^  Ponte 
Vecchio  (Fig.  1 1  )  over  the  Arno  at  Florence  (A.  D.  X'hAbi^^ 


Fig.  11 


and  the  Rialto  (Fig.  187)  at  Venice  (A.  D.  1588)  were 
roofed  over  and  provided  with  shops  on  each  side,  from  which 
merchandise  was  sold.  The  bridges  of  Martorell,  St.  Chamas 
(Fig.  12),  Alcantara,  Saintes,  and  many  others,  had  triumphal 
or  memorial  arches  above  the  roadway.  Others,  like  the  bridge 
of  St.  Benezet  at  Avignon,  had  chapels  at  the  ends  or  side,  and 
many  others  were  guarded  with  fortification  towers.    The  Val- 

29 


30 


ARTISTIC  BRIDGE  DESIGN 


entre  bridge  (Fig.  13)  over  the  Lot  at  Cahors  had  double 
towers  at  the  ends,  and  others  over  the  center  pier.  The  mag- 
nificent bridges  at  Ispahan,  Persia,  which  have  hardly  been  sur- 
passed, had  covered  galleries  or  colonnades  at  each  side,  with 


upper  and  lower  walks,  and  one  of  these  had  a  grand  central 
pavilion.  Later  covered  bridges  with  colonnades  are  those  at 
Pavia,  Italy,  and  the  modern  Auteuil  viaduct  or  Pont  du  Jour 
in  Paris.  The  Pont  de  Chenonceaux,  France  (A.  D.  1556), 
has  six  arches  surmounted  by  a  building  or  castle  of  several 
stories,  the  castle  being  the  most  prominent  feature. 


Fig.  13 

Statuary  is  a  common  adornment  on  the  bridges  of  Paris, 
Berlin  and  other  European  capitals,  instances  being  the  bridge 
of  St.  Angelo  at  Rome,  Trinity  at  Florence,  Pont  Neuf  at 
Paris,  the  Schloss  and  Friedrichs  bridges  in  Berlin.  Features 
of  this  kind  are  notably  absent  in  America,  only  very  few  con- 


SPECIAL  FEATURES  OF  BRIDGES 


31 


taining  anything  more  than  structural  requirements.  Memorial 
bridge  (Fig.  14)  in  Capitol  Park,  Hartford,*  has  a  beautiful 
arch  above  the  roadway  at  one  end,  and  the  new  covered  bridge 
at  Monterey,  Mexico,  has  a  covered  roadway  with  market  stalls 
on  each  side. 

All  of  these  features  and  many  others  are  appropriate.  As 
people  delight  to  congregate  on  a  bridge  in  summer,  foot  walks 
or  promenades  should  be  wide  with  plenty  of  benches  and  occa- 
sional outlooks  in  the  balustrade.     Fountains,  booths  and  rest- 


In  If  ihiL 


Fig.  14 


ing  places,  with  space  for  plants  and  flowers,  may  take  the 
place  of  fortification  towers,  and  shelters  or  lavatories  be  substi- 
tuted for  shrines.  A  central  music  pavilion  would  permit  the 
sound  to  travel  over  the  water  in  the  natural  amphitheatre,  and 
be  enjoyed  by  residents  on  the  neighboring  hill  sides.  Upper 
and  lower  decks  may  sometimes  be  appropriate,  as  on  the 
Girard  avenue  and  Callowhill  bridges  in  Philadelphia,  the 
Eads  bridge  at  St.   Louis,  or  the  proposed  memorial  bridge 

*  H.   G.   Tyrrell,  in  American  Architect,  March  30,   1901. 


Z2  ARTISTIC  BRIDGE  DESIGN 

at  Washington  (Fig.  219).  The  lower  deck,  which  is  suit- 
able for  car  tracks,  may,  in  masonry  bridges,  be  directly  above 
the  main  arches,  and  the  upper  deck  supported  on  open  colon- 
nades, or  the  lower  deck  may  be  the  principal  one,  with  a 
central  arcade  and  elevated  platform  for  cars,  as  on  Pont  du 
Jour  at  Paris  (Fig.  15). 


nnnrYTiTTTTrrrTYTTri 


Fig.  15 

The  best  opportunity  for  large  decorative  features  is  at 
the  portals,  especially  when  the  ends  are  well  exposed.  These 
may  take  the  form  of  entrance  archways,  waiting  pavilions, 
pedestals  and  statues,  or  other  monumental  or  memorial  fea- 
tures suitable  to  the  location.  Hooded  shelters  at  drawbridge 
ends,  with  seats  for  waiting  passengers,  are  useful  and  express- 
ive, and  emphasize  by  their  presence  the  position  of  the  open 
span.  Excellent  examples  of  portal  decorations  are  on  the 
old  Karlsbriicke  (Fig.  185)  at  Prague,  and  the  Bonn 
(Fig.  228),  Diisseldorf  (Fig.  229),  Cologne  (Fig.  241). 
Worms  (Fig.  227),  and  Mayence  bridges  in  Germany.  In 
America,  portal  decoration  seems  to  be  restricted  to  the  plac- 
ing of  lions  or  similar  sculptures  oh  the  ends,  a  practice  common 
in  China  for  centuries,  and  used  by  Stephenson  on  the  Britan- 
nia bridge  (Fig.  16). 

With  abundant  wealth  everywhere  there  is  no  longer  any 
reason  or  excuse  for  confinmg  bridge  design  to  the  calculation 
of  stresses  in  truss  frames,  and  the  erection  of  public  disfig- 
urements. 

KINDS  OF  BRIDGES 

The  cables  of  suspension  bridges  are  in  tension  always, 
and  arch  ribs  are  always  in  compression,  while  beams  and 
trusses  are  subject  to  both  tension  and  compression  and  resist 


SPECIAL  FEATURES  OF  BRIDGES 


33 


bending  by  the  counteracting  moments  in 
the  upper  and  lower  chords.      The  canti- 
lever is  only  a  special  form  of  truss.    Arches 
and    suspension    bridges   with    only    single 
chords  are  lighter  than  truss  bridges,  but 
generally  they  cost  as  much  or  more.      Ma- 
sonry   bridges,    including    those    built    of 
concrete,  are  the  most  permanent,  though 
suitable  for  comparatively  short  spans,  the 
longest   of   any   kind   being   the   328-foot 
reinforced    concrete    arch    just    completed 
(1910)  over  the  Tiber  river  at  Rome,  and 
the  longest  one  of  stone  the  295-foot  arch  at 
Plauen  (Fig.  18),  Germany.  The  proposed 
703-foot  reinforced  concrete  arch    (Figs. 
20-195)    over   Spuyten   Duyvil   creek   at 
CO    New  York  would  contain  more  metal  in  its 
bi    reinforcing  than  would  be  required  to  build 
an  all-steel  arch  of  the  same  length.     Steel 
and  iron,  on  account  of  their  liabihty  to  rust, 
are  less  favored  for  permanent  or  memorial 
bridges  than  masonry,  and  the  two  beau- 
tiful Hudson  Memorial  designs  with  metal 
arches  of  400  and  825  feet   (Figs.  217- 
218)  were  rejected  by  the  Municipal  Art 
Commission  of  New  York  on  that  account. 
When  steel  is  not  painted,  it  will  lose  one- 
quarter  of  an  inch  on  each  face  by  rust  in 
a  century,  and  this  liability  is  its  chief  ob- 
jection.     The  duration  of  metal  bridges 
depends,  therfore,  on  painting,  which  may 
be   overlooked,    or   corrosion   may    attack 
inaccessible  parts.     Of   the   three   metals, 
cast  iron,  wrought  iron,  and  steel,  cast  iron 
is  least  subject  to  rust,  and  steel  the  most 
easily  attacked.     The  most  desirable  ma- 


34 


ARTISTIC  BRIDGE  DESIGN 


terial  is,  therefore,  the  least  permanent.  Ordinary  metal 
bridges  rarely  last  more  than  thirty  to  forty  years,  while  the 
great  monumental  ones  which  are  best  protected  can  hardly  be 
expected  to  endure  more  than  two  or  three  centuries. 


Fig.   17 


A  frequent  objection  to  steel  bridges  is  the  supposed  diffi- 
culty in  beautifying  them,  but  this  is  largely  owing  to  the 
absence  of  precedent  in  this  material.  Art  standards  for  wood 
and  stone  have  been  established  for  centuries,  but  none  were 
available  for  metal. 


SELECTION  OF  PROPER  TYPE 

An  unfortunate  practice,  in  America  at  least,  is  the  making 
insufficient   appropriations    for   constructing   bridges,    and   the 


Fig.  18 


need  of  suiting  the  design  to  the  available  funds.  The  reverse 
method  should  be  followed,  for  the  design  should  first  be  made 
to  suit  the  location  and  the  money  afterwards  provided.   When 


SPECIAL  FEATURES  OF  BRIDGES  35 

appropriations  must  be  made  in  advance,  they  should  be  large 
enough  to  avoid  detrimental  limitations.  It  is  assumed  in  the 
following  pages  that  all  such  limitations  are  absent,  and  that 
the  form  and  type  best  suited  to  the  place  may  be  selected. 
But  even  when  designed  under  a  restricted  cost,  it  is  usually 
possible  to  retain  artistic  features  and  outlines,  and  to  econo- 
mize, if  necessary,  by  making  a  less  width  or  capacity. 

The  principal  features  of  the  bridge  must  be  selected  arbi- 
trarily to  suit  the  requirements.  The  width  of  deck,  number 
of  spans,  and  the  live  load  which  the  bridge  must  support  are 
all  constructive  or  engmeermg  questions,  and  the  amount  of 
aesthetic  or  architectural  treatment  must  also  be  arbitrarily  de- 
termined. The  degree  of  permanence  required  is  another 
prime  factor  greatly  influencing  the  cost.  Long  spans  are 
usually  preferable  to  shorter  ones  for  river  interests,  because 
of  less  obstruction  from  the  piers,  but  when  arches  are  used, 
the  roadway  grade  may  be  so  near  the  water  that  enough  rise 
is  not  available  for  long  spans,  and  shorter  ones  are  then  oblig- 
atory. Long  spans  also  have  a  greater  relative  cost  than  short 
ones,  the  cost  increasing  in  proportion  to  the  square  of  the  span. 
The  Alexander  III.  bridge  (Fig.  72)  at  Paris,  one  of  the 
most  beautiful  in  Europe,  has  insufficient  rise  to  exhibit  an 
appearance  of  strength.  The  outline  resulted  from  a  fixed 
street  grade,  and  a  purpose  to  avoid  river  piers. 

The  degree  of  ornament  must  be  determined  according  to 
the  importance  of  the  location.  In  great  cities,  adjoining  monu- 
mental buildings,  the  beauty  of  the  bridge  should  surpass  or 
at  least  equal  its  surroundings,  so  the  eye  will  naturally  be 
attracted  to  it.  The  same  applies  to  bridges  in  parks  or  private 
estates  where  beauty  is  the  first  essential.  In  such  places  artifi- 
cial lagoons  are  made  as  ornamental  features,  that  they  may 
be  crossed  by  beautiful  bridges,  and  no  limit  should  be  placed 
on  the  amount  of  art  which  may  appropriately  be  displayed. 
Less  ornament  is  generally  sufficient  in  smaller  towns,  and  only 
in  remote  districts,  seldom  or  never  seen,  should  aesthetic  design 
be  neglected. 


36  ARTISTIC  BRIDGE  DESIGN 

The  selection  of  a  proper  outline  will  to  a  great  extent 
determine  its  artistic  merit.  Curves  are  preferable  to  straight 
lines,  and  should  be  adopted  wherever  construction  require- 
ments will  permit.  But  in  choosing  a  form,  and  afterwards  in 
designing  the  bridge,  the  ultimate  object  should  always  be 
kept  in  mind,  which  is,  to  provide  a  platform  of  suitable  width, 
strength  and  beauty,  over  which  travel  may  safely  pass. 

Deck  bridges  are  nearly  always  preferable  to  other  kinds, 
and  should  be  used  in  towns  and  cities  wherever  under  clear- 
ance will  allow.  Through  bridges  obstruct  the  river  view, 
which  is  usually  attractive,  and  the  framing  is  often  the  cause 
of  injury  to  loaded  vehicles,  especially  during  crowded  periods 
or  in  case  of  fire.  Everywhere  in  and  about  American  cities 
numerous  illustrations  exist  of  bridges  unsuited  to  their  loca- 
tion. The  creation  of  a  municipal  art  commission  in  each  city 
should  remedy  much  of  this  evil,  for  these  supervising  bodies 
should  realize  that  fine  monumental  bridges  add  character  and 
distinction  to  their  cities. 


1 


CHAPTER  VI 
Principles  of  Design 

Nature  exhibits  two  distinct  elements  in  her  creations: 
First,  the  constructive,  and  second,  the  aesthetic.  The  first  of 
these  is  purely  utilitarian,  and  in  taking  nature  as  his  guide, 
the  engineer  finds  that  structures  must  first  be  considered  from 
the  constructive  standpoint,  and  attention  given  to  their  capac- 
ity, strength,  economy  and  proportions,  and  the  secondary 
motive  is  their  adornment.  The  great  majority  of  American 
bridges  have  unfortunately  been  planned  w^ith  no  thought  what- 
ever for  their  appearance,  merely  as  "tools  of  transportation." 
But  the  age  of  design  by  mathematics  only,  has  fortunately 
passed,  and  the  era  of  a  higher  ideal  in  bridge  design  has  been 
revived. 

It  is  generally  easier  to  beautify  a  simple  structure  than 
one  containing  difFerent  materials,  for  in  the  latter  case  the 
light  framing  is  apt  to  clash  too  seriously  with  the  heavier 
masonry.  The  contrast  is  illustrated  in  the  825-foot  arch 
design  for  the  Hudson  Memorial  bridge  at  New  York 
(Fig.  218). 

CO-OPERATION  OF  ENGINEER  AND  ARCHITECT 

In  large  or  important  bridges,  unless  the  engineer  himself 
is  proficient  in  aesthetics,  which  is  seldom  the  case,  it  is  better 
to  have  an  architect  associated  on  the  work  from  the  first,  not 
merely  to  decorate  the  bridge  after  the  engineer's  work  is  fin- 
ished, but  to  assist  in  the  design  from  its  inception.  If  a  wrong 
outline  be  selected  in  the  beginning,  no  effort  of  the  architect 
and  no  amount  of  decoration  can  remedy  the  error  or  make  a 
beautiful  bridge  of  an  ugly  one.  But  when  aesthetics  are  con- 
sidered from  the  start,  the  design  should  then  develop  harmo- 

38 


PRINCIPLES  OF  DESIGN 


39 


niously  into  beautiful  con- 
struction. Unfortunately,  a 
lack  of  harmony  between  the 
two  professions  has  been  a 
hindrance  to  successful  co- 
operation, for  the  architect 
declared  that  the  only 
bridges  with  any  real  beauty 
are  those  which  antedate  the 
days  of  engineering,  while 
the  engineers  know  that 
nearly  all  the  great  modern 
bridges  are  the  work  of  en- 
gineers alone,  and  that  to  en- 
gineers more  than  and  other 
class  is  due  the  rapid  pro- 
gress of  the  last  century. 
The  members  of  each  pro- 
fession now  realize  that  all 
their  time  is  occupied  in  mast- 
ering their  own  special 
studies,  and  the  engineer  is 
willing  to  admit  himself  de- 
ficient in  the  training  of  his 
aesthetic  taste,  and  the  archi- 
tect confesses  his  lack  of  con- 
structive knowledge.  With 
this  mutual  understanding, 
there  should  be  no  more  dif- 
ficulty in  working  harmoni- 
ously together  on  bridges 
than  on  buildings,  which  is 
already  a  common  practice. 
The  finest  designs  ever  pro- 
duced in  America  are  those 
which     are     the     combined 


40 


ARTISTIC  BRIDGE  DESIGN 


work  of  engineers  and  architects,  including  the  memorial  bridge 
designs  (Figs.  21-22)  for  Washington,  and  the  several  bridges 
for  New  York  City.  It  is  now  plain  that  the  great  bridges  of 
the  future  will  not  be  the  product  of  either  engineer  or  archi- 


tect alone,  but  of  both  combined.  That  this  condition  of 
cooperation  now  exists  in  Germany  is  clearly  shown  by  some 
of  the  recent  bridges  in  that  country,  including  those  at  Worms 
(Fig.  227),  Mainz  (Fig.  230),  Diisseldorf  (Fig.  229),  and 
Cologne  (Fig.  241  ).  The  railroads,  which  have  been  amongst 
the  worst  offenders  in  America,  no  longer  leave  the  design  of 


Z  'A 


Pig.  22 

stations  and  other  buildings  wholly  to  engineers,  but  use  the 
combined  service  of  engineers  and  architects,  and  the  same 
cooperation  must  soon  apply  to  bridges,  which  are  frequently 
more  conspicuous  than  stations.  It  will  then  be  no  longer  pos- 
sible for  a  "professional  vandal"  to  be  an  eminent  engineer. 


PRINCIPLES  OF  DESIGN  41 

The  artistic  motive  is  not  the  prevaihng  one  and  must  be 
subservient  to  construction,  but  it  must  not  be  neglected.  The 
tendency  in  architecture  is  frequently  to  add  excess  material 
in  order  to  secure  satisfactory  proportions,  while  the  object  of 
the  engineer  is  usually  to  eliminate  all  useless  weight,  which 
only  requires  additional  framing  to  sustain  it.  It  is  only  by 
working  together  that  correct  results  are  obtained.  Factory 
designing  of  bridges  resulted  in  much  economy,  and  competi- 
tions were  the  cause  of  great  progress,  but  the  relation  of  engi- 
neer to  factory  or  bridge  shop  now  should  be  precisely  the 
same  as  the  corresponding  relation  between  architect  and  build- 
ing contractor. 

GENERAL  DIMENSIONS 

The  purpose  of  a  bridge  should  at  all  times  be  kept  in 
mind  during  the  progress  of  the  design,  the  object  being  to 
construct  a  platform  of  suitable  strength  and  width  to  convey 
travel  safely,  and  at  the  same  time  provide  openings  under  the 
bridge  suitable  to  the  local  requirements.  Small  spans  are 
no  longer  desirable,  though  they  may  sometimes  be  permitted 
over  quiet  water.  Long  spans  are  demanded  for  river  travel 
and  commerce,  or  for  crossing  deep  or  rapid  water.  The 
span  lengths  should  seem  to  fit  the  river  width,  for  if  longer, 
they  appear  excessive,  and  if  shorter,  they  look  insufficient. 
Deck  bridges  are  preferable  to  through  bridges,  for  framing 
above  the  floor  is  an  obstruction  to  the  river  view,  and  a  menace 
to  travel.  Panels  or  other  subdivisions  should  be  proportioned 
to  the  whole.  The  arrangement  and  grouping  of  spans  should 
be  carefully  considered,  and  the  same  kind  of  construction  used 
to  meet  similar  conditions. 

PIERS 

A  bridge  with  too  many  piers  (Fig.  23)  is  little  else  than  a 
perforated  dam,  and  it  is  a  serious  obstruction  in  running  or 
navigable  water.  The  thickness  of  piers  should  be  carefully 
proportioned  to  their  height,   and  base  courses  and  copings 


42 


ARTISTIC  BRIDGE  DESIGN 


suited  to  the  pier  body.  The  height  of  substructure  and  super- 
structure should  also  be  proportioned  to  each  other.  Double 
cut-waters,  though  not  a  structural  requirement  excepting  in 


m 


^^ 


m 


w 


lypp 


z^^ 


] — [ 


] — [ 


] — [ 


Fig.  23 

tidal  channels,  give  a  more  symmetrical  appearance,  and  may 
prevent  scour  on  the  rear  end  of  piers. 

PRINCIPLES  OF  DESIGN 

The  general  principles  of  artistic  design  are: 

1 .     The  selection  of  the  most  artistic  form  consistent 
with  economy. 
Expressiveness. 
Symmetry. 
Simplicity. 

Harmony  and  contrast. 
Conformity  with  environment. 
Proper  combination  of  materials. 
A  judicious  use  of  applied  ornament. 

1 .  The  elevation  of  a  bridge  is  more  seen  than  any  other 
view,  and  spectators  are  most  impressed  by  its  general  oudine 
and  proportions.  If  a  wrong  outline  be  selected,  the  effect 
artistically  is  sure  to  be  a  failure,  for  no  amount  of  detail  or 
applied  ornament  can  remedy  the  error.  And  yet  in  some 
cases  where  straight  lines  are  imperative  applied  ornament  may 
be  effective  and  is  permissible,  as  in  the  Forest  Park  entrance 
bridge  at  St.  Louis  (Fig.  24).  Where  artistic  form  and  out- 
line are  obtainable,  as  in  a  great  suspension  bridge  with  cam- 
bered floor,  the  outline  may  in  itself  be  sufficient,  without  any 
applied  detail.  In  fact,  small  ornamentation  on  great  struc- 
tures frequently  produces  a  diminutive  effect,  and  is  not  desir- 
able.    Structural  requirements  must  predominate,  especially  m 


2. 
3. 
4. 

5. 
6. 
7. 
8. 


PRINCIPLES  OF  DESIGN 


43 


large  bridges,  and  even  though  the  public  now  lacks  apprecia- 
tion for  correct  structural  forms,  the  vital  principle  must  be 
maintained  that  "there  is  beauty  in  any  useful  structure  de- 
signed on  lines  of  true  economy  with  the  utmost  simplicity  and 


Fig.  24 


fewest  parts."  TTie  best  effect  is  secured  from  the  most  pleas- 
ing outline  consistent  with  economy,  and  a  very  limited  use  of 
applied  ornament.     The  aesthetic  outline  may  be  close  enough 


Pis.  25 


to  structural  requirements  to  be  quite  as  effective,  and  have 
no  greater  cost.  From  the  standpoint  of  beauty,  curves  are 
always  preferable  to  straight  lines,  and  of  certain  forms  like 
the  semicircle  or  ellipse  the  eye  never  tires.    When  arches  are 


44 


ARTISTIC  BRIDGE  DESIGN 


impossible,  a  decided  camber  on  a  truss  or 
girder  is  often  effective.  The  upward  curve 
of  the  floor  lends  as  much  beauty  to  the  Brook- 
lyn bridge  (Fig.  235)  as  the  downward  sweep 
of  the  cables.  The  beautiful  park  bridge  at 
Madison,  N.  J.*  (Fig.  25),  has  cambered 
girders,  the  satisfactory  effect  of  which  cannot 
be  questioned.  In  any  case,  to  avoid  the 
appearance  of  sag,  a  small  floor  camber  is 
desirable. 

Similar  means  should  be  used  towards 
similar  ends,  but  a  change  of  constructive  form 
should  not  be  made  without  an  evident  purpose. 
Small  side  arches  may  adjoin  large  central 
ones,  where  the  height  changes,  as  in  crossing  a 
valley.  An  uneven  number  of  spans  is  always 
preferable  (Fig.  26),  for  the  eye  is  better  satis- 
fied with  an  opening  rather  than  a  pier  at  the 
center.  Bridges  with  several  spans  should  have 
the  longest  at  the  center,  and  adjoining  ones 
should  decrease  in  length  toward  the  ends. 


EXPRESSIVENESS 

2.  Expressiveness  in  a  structure  is,  with 
-^  many  people,  the  greatest  element  of  beauty, 
and  the  visible  parts  and  lines  should  show  their 
purpose.  Imitation  and  deception  are  most 
contemptible  when  carried  out  in  constructive 
-  forms.  A  bridge  must  be  a  truthful  creation 
I  and  its  appearance  should  show  its  purpose. 
-|  If  the  spandrels  of  a  masonry  bridge  are  hollow 
-^~  they  should  so  appear,  and  should  not  be  con- 
cealed with  curtain  walls.  As  strength  is  a 
chief  requisite,  this  element  should  be  emphasized.  Some 
recent  metropolitan  bridges  of  long  span,  where  only  a  small 

*  H.  G.   Tyrrell,  in  The  Engineer,  London,  Nov.,  1900;  Engineering  News, 
Aug.,  1900. 


PRINCIPLES  OF  DESIGN 


45 


rise  was  available,  lack  the  appearance  of  strength  and  fail 
to  impress  an  observer  with  a  feeling  of  security.  Expres- 
siveness is  also  obtained  through  special  or  ornamental  features. 
A  memorial  bridge  relates  its  own  story  by  its  statues,  friezes, 
and  inscriptions.  Sentimental  or  historical  traditions  are  well 
illustrated  on  the  portals  of  many  European  bridges,  such  as 
those  at  Kehl,  Bonn,  and  Mayence.  The  Gothic  portal  of  the 
Kehl  bridge  (Fig.  242),  somewhat  resembling  cathedral  archi- 
tecture, might  be  a  historical  representation  of  the  times  when 
bridges  were  erected  and  preserved  by  the  clergy  of  Pontifices, 
under  the  direction  of  the  Pontifex  Maximus.  Remains  of 
many  bridges  built  by  this  religious  order  are  still  extant.  Com- 
binations of  different  types  in  one  structure  such  as  in  the  arch- 
cantilever,  or  in  the  arch  truss  which  was  common  in  wooden 
bridges,  are  lacking  in  simplicity  and  definite  action,  and  such 
forms  are  therefore  not  so  desirable  as  single  systems.  Expres- 
siveness is  very  easily  obtained  in  the  abutments  of  metal  arch 
bridges,  which  may  be  made  of  such  size  and  form  as  to  clearly 
show  their  duty  and  action.  In  this  case  extreme  economy  may 
sometimes  be  ignored  for  the  sake  of  emphasizing  the  abutment 
action. 


SYMMETRY  AND  SIMPLICITY 

3.  One  or  the  most  important  factors  of  good  design  is 
symmetry.  If  conditions  will  at  all  permit,  the  general  outline 
on  each  side  of  the  center  should  be  the  same,  or  nearly  so 


(Fig.  27).  It  should  at  least  partake  of  the  same  general 
arrangement  in  reference  to  the  number  and  length  of  spans. 
There  is  no  greater  jar  to  aesthetic  feeling  than  to  see  a  bridge 


46 


ARTISTIC  BRIDGE  DESIGN 


in  which  this  principle  is  violated,  with  large  spans  at  one  end 
and  smaller  spans  at  the  other,  or  with  the  principal  span  notice- 
ably out  of  center  (Fig.  28).  The  beautiful  design  for  the 
proposed  Hudson  Memorial  bridge  (Fig.  20)  is  unfortunately 
marred  by  an  unsymmetrical  ground  contour,  necessitating 
approaches  of  different  lengths.     The  presence  or  absence  of 


Fig.   28 


symmetry,  and  the  resulting  effect,  is  well  illustrated  by  the 
many  designs  for  the  Washington  bridge  at  New  York.  Those 
in  which  symmetry  is  observed  are  satisfying,  while  others 
are  not.  The  absence  of  symmetry  should  be  permitted  only 
when  the  ground  contour  or  other  conditions  are  such  as  to 
make  a  symmetrical  arrangement  impossible.  Sub  aqueous 
conditions  may  necessitate  an  uneven  arrangement  of  spans, 
but  as  the  reason  for  the  change  in  such  cases  is  not  evident, 
the  design  is  aesthetically  unsatisfactory. 

4.  Simplicity  is  important,  though  not  so  essential  as  sym- 
metry. Too  many  members  are  confusing,  and  a  less  number 
of  larger  pieces  are  preferable.  The  confusing  effect  is  best 
realized  when  a  bridge  is  viewed  in  perspective,  from  which 
position  the  bracing  in  all  directions  is  evident,  and  the  lines 
may  appear  to  cross  each  other  at  many  angles. 

HARMONY  AND  CONTRAST 

5.  An  abrupt  change  is  sometimes  better  than  a  gradual 
one.  When  approaches  are  of  very  different  construction 
from  that  of  the  central  span,  the  two  should  be  conspicuously 
divided  (Fig.  29),  as  with  a  heavy  pier.  Short  end  spans 
should  have  a  character  of  their  own  and  not  be  miniatures  of 
the  larger  ones.     Spans  arranged  in  groups  produce  a  better 


PRINCIPLES  OF  DESIGN 


47 


effect  than  a  succession  of  similar  ones,  and  groups  should  pref- 
erably contain  three  spans  or  more.  The  comparative  aesthetic 
effect  is  exemplified  in  tall  viaducts.  Those  in  which  alternate 
long  and  short  spans  are  supported  on  braced  towers  appear 
better  than  a  succession  of  equal  length  bays,  the  improvement 
being  due  to  contrast.  The  type  of  construction  should  not 
change  unless  the  reason  for  such  change  is  evident,  as  in  the 


Fig.  29 


use  of  steel  framing  for  the  center  span  of  a  stone  viaduct. 
Some  of  the  competitive  designs  for  the  Washington  bridge 
proposed,  with  insufficient  reason,  very  mixed  types  of  con- 
struction, and  the  artistic  effect  was  thereby  injured. 

CONFORMITY  TO  ENVIRONMENT 

6.  A  highly  ornamental  bridge  would  be  inappropriate 
in  a  rough  district,  and  an  unsightly  truss  bridge  is  out  of  place 
in  a  park  or  city  among  beautiful  surroundings.  In  a  wild 
mountain  region  the  bridge  should  be  bold,  while  in  a  park 
it  should  contain  fine  ornament,  and  have  a  more  finished 
appearance.  The  rule,  generally,  is  to  make  the  bridge  more 
striking  than  its  surroundings,  so  the  eye  will  be  naturally 
attracted  to  it.  The  modern  method  is  to  make  separate  photo- 
graphs of  the  site  and  the  design  to  the  same  scale,  and  after 
placing  the  proposed  bridge  in  the  landscape  view,  to  rephoto- 
graph  the  combination.  Features  of  the  design  which  fail  to 
conform  with  the  surroundings  will  then  appear,  and  changes 
can  be  made  until  it  is  satisfactory.  The  Conway  suspension 
bridge  (Fig.  233)  is  an  excellent  example  of  one  harmonizing 


48 


ARTISTIC  BRIDGE  DESIGN 


with  its  surroundings,  the  towers  being  made  to  resemble  those 
in  the  adjoining  castle.  The  architecture  of  the  Tower  bridge 
(Fig.  83)  was  intended  to  conform  with  the  near-by  Tower 
of  London,  and  the  Saintes  bridge  (Fig.  30)  over  the  Charente 
had  triumphal  arches  over  the  roadway  similar  to  the  openings 
in  the  adjoining  castle  wall.    A  rustic  bridge  of  either  wood  or 

stone  is  appropriate  in  a 
wooded  park  or  rural  dis- 
trict. In  a  park  with  rough 
and  rocky  surroundings,  no 
form  is  more  suitable  than  a 
bold-faced  masonry  arch, 
while  in  a  garden  or  private 
estate  surrounded  by  land- 
scape gardening,  a  finer  class 
of  work  would  naturally  be 
preferred.  In  the  latter  case, 
stone  work  would  be  finely 
cut  ornamented  with  corner 
and  belt  courses,  and  the 
road  guarded  with  a  highly 
ornamented  railing.  Land- 
scape gardening  about*  the 
approaches  adds  greatly  to 
its  beauty,  and  should  be 
carried  out  when  possible.  In  any  case,  even  in  rural  or  out- 
lying districts,  the  site  should  be  cleaned  up  and  left  in  a  trim 
and  neat  condition.  The  principle  of  conformity  to  landscape 
is  therefore  one  of  the  most  important. 


MATERIAL  AND  COLORS 

7.  The  laws  of  harmony  and  contrast  apply  also  to  the 
selection  of  material  and  colors.  Heavy  projections  and  deep 
shadows  produce  an  effect  of  strength  which  is  not  easily 
secured  without  them. 

Color  combinations  produce  harmony  or  discord  on  the 


PRINCIPLES  OF  DESIGN  49 

senses  similar  to  combinations  of  sounds.  Soft  colors  are  pref- 
erable to  bright  ones,  and  if  two  or  more  are  used,  they  should, 
if  possible,  emphasize  the  construction  lines.  The  arch  stones 
and  trimmings  may  be  of  one  colored  material,  and  the  span- 
drel walls  of  another.  If  paint  is  used  on  wood  or  metal,  it 
should  harmonize  with  the  stonework  and  surroundings.  Con- 
crete blocks,  hard  brick  in  different  shades,  cut  stone  and  con- 
crete of  different  tones  may  all  be  used  to  good  effect. 

USE  OF  ORNAMENT 

8.  A  distinction  must  be  made  between  those  structures 
which  are  naturally  graceful,  and  others  on  which  decoration 
is  evident.  A  design  should  please  without  apparent  effort. 
Ruskin's  rule  to  "decorate  construction  without  constructing 
decoration"  applies  to  bridges  as  well  as  buildings.  Super- 
fluous ornament  may  render  a  bridge  ridiculous,  and  an  excess- 
ive amount,  especially  on  large  ones,  is  not  commended,  though 
a  judicious  use  is  right  and  fitting.  In  this  matter,  nature  must 
again  be  the  guide.  The  skeleton  of  trees  or  plants  are  covered 
with  leaves  and  flowers,  and  the  rough  hill  sides  with  beauty 
and  verdure.  So  with  structures,  a  limited  amount  of  orna- 
mental features  is  appropriate,  but  excessive  ornament  which 
would  add  greatly  to  the  imposed  loads  cannot  be  permitted, 
especially  on  framed  bridges,  as  all  added  weight  requires  extra 
framing  to  support  it.  The  use  of  ornament  to  this  extent  is 
contrary  to  the  fundamental  principle  of  economy.  For  this 
reason,  very  little  or  no  heavy  ornament  should  be  allowed  on 
steel  spans  between  the  piers.  Small  decorative  features  are 
suitable  only  when  they  can  be  closely  observed,  as  on  the 
balustrade  or  railing.  Panels  should  be  either  square  or  decid- 
edly long.  Features  which  can  be  seen  only  from  a  distance 
should  be  large,  or  the  general  form  or  outline  may  supply  the 
only  ornamentation.  The  ends  or  portals  offer  the  greatest 
opportunity  for  embellishment.  In  this  position,  weight  is  not 
added  to  the  bridge,  but  only  to  the  piers  or  abutments,  and  as 
the  ends  are  usually  exposed,  decorative  features  are  easily 
seen. 


CHAPTER  VII 

Ordinary  Steel  Structures 

Large  metal  bridges  should  always  be  proportioned  accord- 
ing to  the  rules  of  economy  and  service,  depending  for  their 
artistic  effect  on  their  general  form,  and  very  large  spans  must 
always  be  framed  in  steel.  Steel  bridges  have  not  been  long 
enough  used  to  win  for  themselves  the  public  appreciation 
which  they  deserve,  and  when  better  understood  they  will  be 
more  admired.  A  limited  amount  of  ornament  may  be  used 
on  the  spans  and  on  the  balustrade,  lamps,  trolley  poles  or 
brackets;  and  a  large  amount  on  or  above  the  piers.  Framed 
bridges  should  have  the  smallest  possible  number  of  parts, 
for  excessive  bracing  appears  confusing,  and  when  viewed 
obliquely  the  lines  seem  to  lack  proper  arrangement.  Arches 
and  suspensions  are  the  most  artistic  forms,  though  cantilevers 
with  curved  outlines  like  those  at  Budapest  and  Pittsburg  may 
be  equally  pleasing.  Skew  bridges  should,  if  possible,  be 
avoided.  Steel  bridges  are  usually  more  difficult  to  beautify 
than  masonry,  and  their  chief  interest  must  result  from  their 
outline.  The  need  of  painting  is  the  chief  objection  to  metal, 
for  if  this  be  neglected,  the  metal  soon  deteriorates.  Half 
through  girders  are  improved  when  the  outer  ends  are  curved  to 
a  quarter  circle. 

BEAM  BRIDGES 

Small  spans  are  worthy  of  careful  consideration  and  treat- 
ment, for  they  greatly  outnumber  the  larger  ones,  and  hori- 
zontal beams  are  frequently  necessary  to  give  the  proper  height 
below.  Beam  bridges  are  much  used  for  street  subways  under 
railroad  tracks  where  the  latter  are  elevated  on  banks  to  avoid 
level  crossings.     In  such  cases,  the  required  head  room  above 

50 


ORDINARY  STEEL  STRUCTURES 


51 


the  street  is  first  established,  and  adding  to  this  the  thickness 
of  the  floor,  gives  the  height  of  track  above  the  street.  It  is 
frequently  desirable  to  use  a  thin  floor,  for  any  increased  thick- 
ness would  raise  the  height  of  the  whole  embankment  by  the 
same  amount.  When  the  span  is  long  enough  to  require  a 
greater  depth  for  the  main  girders  than  can  be  allowed  beneath 


the  upper  floor  or  track,  half-through  framing  may  be  necessary, 
with  a  system  of  floor  beams  supported  by  side  girders  far 
enough  apart  for  track  clearance.  This  arangement  was  used 
at  the  entrance  to  Forest  Park,  St.  Louis  (Fig.  24),  the  steel 
girders  being  concealed  by  an  outside  ornamental  concrete 
facing.  As  the  side  area  of  the  beams  is  usually  small,  the 
chief  opportunity  for  adornment  is  on  the  abutments  and 
balustrade.     That  good  effect  can  be  secured  is  shown  by  the 


illustrations.  Fig.  25,  with  side  girders  in  arch  form,  is  not  as 
sincere  as  Fig.  24,  and  over  a  street  the  curved  soffit  might  leave 
insufficient  head  room  above  the  sidewalk,  but  it  nevertheless 


52 


ARTISTIC  BRIDGE  DESIGN 


ORDINARY  STEEL  STRUCTURES 


53 


looks  well.  The  writer's  three  original  designs  in  reinforced 
concrete  (Figs.  31-32-33)  show  some  other  possibilities  with 
this  type,  the  first  two  being  well  suited  for  parks. 

TRUSS  BRIDGES 

A  few  years  ago  most  truss  forms  were  patented,  and  the 
outline  of  a  bridge  at  once  revealed  its  originator.  But  the 
process  of  elimination  has  been  active,  and  a  few  only  of  the 


.^j^roa>a^^^ 


Fig.   34 


most  approved  forms  are  now  favored  for  ordinary  spans, 
though  special  study  is  usually  given  to  longer  ones.  Trusses 
have  a  greater  weight  than  arches  or  suspensions,  but  their 


■  ITpaneh  of  27- 4k" '  4«S-e4'e.ile. 
Fig.  35 


cost  is  generally  less  than  either.  Upper  chords  when  curved 
should  have  the  principal  panel  points  on  a  parabola  (Fig. 
34*),  with  straight  sections  between,  and  in  the  case  of 
through  truss  bridges  the  curves  should  continue  only  between 


Fig.  36 


the  upper  ends  of  inclined  end  posts,  and  not  down  to  the 
shoes.  If  the  end  posts  are  a  continuation  of  the  upper  chord 
curve,  their  inclination  is  not  sufficient  to  produce  a  sense  of 
strength  and  security.     Figs.  35  and  36  have  insufficient  end 


*  Elizabethtown  Bridge. 

*  H.    G.   Tyrrell,    in    Canadian    Engineer,    November,    1909. 


54 


ARTISTIC  BRIDGE  DESIGN 


depth  for  appearance,  and  too 
many  web  members,  the  double 
panels  and  simpler  outline  of 
Fig.  34  being  more  satisfying 
and  preferable.  Trusses  with 
curved  upper  chords  and  ties  at 
or  below  the  floor  level,  like 
those  at  Mainz  and  Worms, 
are  meeting  with  much  favor 
in  Europe,  but  are  discussed 
under  Arches,  because  of  their 
close  resemblance  to  the  true 
arch  bridges  at  Bonn  and  Diis- 
seldorf,  which  have  inclined 
pier  thrusts.  Curved  connec- 
tion plates  in  trusses  must  have 
curves  tangent  to  the  members, 
and  not  segmental.  Other  gen- 
eral principles  of  artistic  design, 
such  as  symmetry  and  simplic- 
ity, should  be  applied  wherever 
possible.  The  inclination  of 
web  members  should  be  as 
nearly  uniform  as  possible,  ap- 
proaching an  angle  of  45  de- 
grees, but  uniform  inclinations 
should  not  be  obtained  at  a 
sacrifice  of  simplicity  in  the 
floor  system.  In  designing  the 
586-foot  trusses  of  the  Eliza- 
bethtown  bridge,  an  outline 
was  considered  with  diagonals 
at  uniform  inclinations,  and 
panels  increasing  in  length 
towards  the  center,  but  on  ac- 
count of  the  irregularity  which 


ORDINARY  STEEL  STRUCTURES 


55 


would  result  to  the  floor  system,  it  was  not  favored.  The 
plan  has,  however,  been  carried  out  since  in  the  trusses  on 
the  Municipal  bridge  at  St.  Louis. 

VIADUCTS  AND  TRESTLES 

The  best  effect  in  this  class  of  structures  is  secured  when  the 
length  of  intermediate  spans  is  great  in  proportion  to  the  length 
of  towers,  as  in  the  Fribourg  viaduct  in  Switzerland,  or  the 
Dowery  Dell  in  England.  When  the  length  of  tower  and 
intermediate  spans  are  the  same  or  nearly  equal,  as  in  the 
artistically  unfortunate  viaduct   (Fig.  38)   recently  erected  in 


Fig.  39 

Northwestern  Canada,  all  semblance  to  beauty  is  lost.  Inter- 
mediate spans  may  have  curved  bottom  chords,  as  in  the  high 
viaduct  (Fig.  37)  designed  by  the  writer  for  the  Montreal 
river  crossing  in  Algoma.*  They  have  the  additional  merit  of 
facilitating  erection  by  their  cantilever  action,  and  permitting 
the   use   of   a   comparatively   short  boom  traveller.      Towers 


Fig.   40 


should  have  the  necessary  transverse  batter,  and  a  slight  longi- 
tundinal  taper  of  about  half  inch  per  vertical  foot,  on  each 
column.  The  comparative  aesthetic  effect  of  towers  with  and 
without  longitudinal  column  batter,  is  seen  by  comparing  Figs. 
37,  39  and  42  with  38  and  41 .  Towers  with  vertical  bents 
have  an  awkward  or  top-heavy  appearance.     Fig.  39,  designed 

*  Economic  length  of  trestle  spans. 

*  H.  G.  Tyrrell,  in  Railroad  Gazette,  December,  1904. 


56 


ARTISTIC  BRIDGE  DESIGN 


by  the  writer  for  heavy  railroad  travel  over  Salmon  river  gorge, 
represents  the  best  American  practice.  The  extra  cost  of  shop 
work  on  the  connection  plates  is  small,  and  is  warranted  by  the 
improved  appearance.  Fig.  40,  part  of  the  writer's  design 
for  a  2, 600- foot  viaduct  at  Ogden,  is  a  form  which  is  suitable 
for  carrying  streets  over  railroad  yards,  the  curved  bottom 
chords  having  a  better  effect  than  horizontal  ones.  It  is  good 
practice  to  use  abutment  piers  at  intervals  of  three  to  five  spans, 
and  these  may  be  of  metal  or  masonry,  as  desired. 


MOVABLE  BRIDGES  / 

Ugliness  in  bridge  design  may  usually  be  attributed  either 
to  the  incompetence  of  the  designer  or  to  the  restrictions  imposed 
upon  him  which  are  beyond  his  control.     The  latter  excuse  is. 


Fig.  41 


Fig.  42 


however,  too  frequently  offered  where  it  is  not  sufficient.   Some 
of  these  limitations  are  as  follows : 

( 1  )  Number  of  decks  and  their  relative  position. 

(2)  Elevation  of  deck  above  water. 

(3)  Under  clearance  required. 

(4)  Angle  of  crossing,  whether  square  or  skew. 

(5)  Grade. 

A  great  many  kinds  of  opening  bridges  have  been  devised, 
and  it  is  difficult  to  conceive  of  new  forms  which  have  not  been 
previously  used.     In  fact,  most  of  the  patented  inventions  of 


ORDINARY  STEEL  STRUCTURES 


57 


the  last  twenty  years  are  merely  revivals  of  projects  which 
were  studied  out  or  buijt  by  others  during  the  last  century. 
Many  features  of  modern  bridges,  originality  for  which  is 
claimed  by  recent  proprietors,  may  be  found  in  use  before  the 
advent  of  the  present  generation,  and  there  is,  therefore,  no 
branch  of  engineering  in  which  a  knowledge  of  history  is  more 
essential. 

Movable  bridges  show  a  greater  lack  of  aesthetic  treatment 
than  almost  any  other  form,  and  many  of  them  are  about  as 
ugly  as  could  be  imagined.  Like  other  kinds,  they  must 
depend  chiefly  on  their  outline  for  their  appearance,  and  their 
form  should,  so  far  as  possible,  show  their  purpose  and  action. 
If  a  wrong  outline  is  chosen,  no  amount  of  after-treatment  can 
remedy  the  error,  as  was  so  well  proven  by  the  balanced  bridge 
over  the  Royal  Canal  at  Dublin. 


Fig.   43 


Each  individual  case  requires  different  treatment,  and  a 
form  which  would  be  most  suitable  for  one  location  might  be 
quite  unsuited  to  another.  Bridges  in  cities  like  Chicago, 
London  and  Berlin,  where  the  land  adjoining  the  river  is  low, 
are  perhaps  the  most  difficult  to  treat  satisfactorily;  and  yet 
these  cities,  especially  the  last,  have  many  examples  of  much 
merit. 

The  number  of  decks  and  their  height  above  the  water, 
greatly  influences  the  design,  and  the  required  under-clearance 
will  usually  fix  the  bottom  outline.  Deck  bridges  are  nearly 
always  preferable  to  through  ones,  and  should  be  used  wherever 


58 


ARTISTIC  BRIDGE  DESIGN 


•  ORDINARY  STEEL  STRUCTURES  59 

enough  height  is  obtainable  beneath  the  floor  for  framing. 
Parts  above  the  deck  obstruct  the  view,  and  may  be  a  serious 
hindrance  to  travel,  especially  during  crowded  hours  or  in  such 
emergencies  as  fire.  When  enough  height  is  available,  a  curved 
form  generally  looks  better  than  a  straight  one,  though  the 
latter  leaves  more  space  for  the  passage  of  boats  and  river  craft. 
The  height  of  floor  above  water,  the  length  of  span  and  number 
of  leaves,  will  also  determine  whether  the  floor  must  be  above 
the  principals  or  between  them.  The  design  is  also  influenced 
by  the  angle  of  the  crossmg,  whether  squared  or  skewed,  and 
by  the  approach  grades.  In  some  cases,  where  the  piers  must 
stand  parallel  with  the  current,  the  angle  of  the  skew  may  be 
small  enough  that  the  ends  above  the  piers  may  be  arranged  as 
though  the  bridge  were  square,  enough  space  being  available 
on  the  top  of  piers  for  arranging  the  shoes  to  the  proper  angle. 
In  any  case,  skewed  end  panels,  as  on  the  bascule  over  Fort 
Point  channel,  Boston,  and  near  Kinzie  street,  Chicago,  should 
be  avoided  where  possible. 

Features  which  may  usually  be  arbitrarily  selected  are : 

( 1  )  Number  of  principals. 

(2)  Kind  of  principals,  truss  or  girder. 

(3)  Number  of  leaves. 

(4)  Outline  of  principals. 

(5)  Bracing. 

The  surroundings  of  a  structure  greatly  affect  its  appearance. 
They  should  always  be  neat,  and,  when  possible,  should  have 
enough  open  space  adjoining  so  the  bridge  will  stand  out  con- 
spicuously. Landscape  gardening  at  the  ends  is  most  appro- 
priate, such  as  may  be  seen  adjoining  the  old  Budapest 
suspension. 

Double  leaf  bascule  bridges  are  the  best  form  for  decora- 
tive treatment,  for  the  outline  of  the  two  leaves  can  be  made 
to  correspond  with  the  curves  of  the  adjoining  spans.  Single 
leaf  bascules  are  not  artistic,  for  they  lack  symmetry,  but  an 
effort  must   be   made   to  beautify   them   if   any   grace   is   to 


60 


ARTISTIC  BRIDGE  DESIGN 


ORDINARY  STEEL  STRUCTURES  61 

appear.  Combined  bascule  and  cantilever,  such  as  those  pat- 
ented by  Messrs.  Shaw  and  Newton,  have  a  greater  clear  width 
between  the  piers,  but  the  leaves  when  raised  are  unprotected, 
and  none  of  this  kind  have  yet  been  constructed. 

A  curved  outline  for  the  bottom  chord  usually  looks  well 
(Figs.  44-46),  and  is  suitable  when  the  necessary  height  is 
obtainable,  the  form  being  used  in  1839  for  the  Ouse  river 
bridge  at  Selby,  which  acted  as  a  true  arch  under  live  loads. 
In  other  cases,  through  arches  can  be  used,  as  at  Stettin  over 
the  Oder,  completed  1905,  and  at  St.  Petersburg  over  the 
Neva;  a  somewhat  similar  one  (Fig.  45)  being  proposed  in 
1906,  to  cross  the  Potomac  at  Washington.  Double  canti- 
levers with  a  horizontal  bottom  chord  and  a  curved  upper  one 
following  the  lines  of  a  stiff  suspension,  are  used  for  bascule 
bridges  over  Newton  creek  at  New  York  and  at  Twenty- 
second  street,  Chicago,  and,  as  far  as  outline  is  concerned,  are 
fairly  satisfactory. 

The  number  of  leaves  depends  chiefly  on  the  length  of  span, 
single  ones  being  suitable  up  to  about  1  50  feet.  For  appear- 
ance, two  are  preferable  to  one,  as  the  arrangement  is  then 
symmetrical,  besides  making  a  deck  structure  possible,  where 
a  single  leaf  might  need  through  trusses.  Though  more 
expensive,  two  are  always  preferable  to  one  for  highway 
bridges,  and  the  leaves,  when  raised,  form  a  substantial  barrier 
against  road  travel.  But  double  leaves  are  not  suitable  under 
trains  and  locomotives,  as  the  center  connection  is  too  uncer- 
tain, and  liable  to  cause  derailment.  A  double  leaf  bridge  for 
heavy  loads  was  used  at  Rhyl  previous  to  1871,  and  proved 
to  be  a  mechanical  failure  because  the  center  lock  was  insuffi- 
ciently secure.  The  Fijinoord  bascule  at  Rotterdam  (1875) 
and  the  later  one  at  Duisburg  (1906)  have  tv^o  double-leaf 
bascules,  close  together,  the  latter  having  space  between  the 
adjoining  bridges  for  the  operators'  house. 

Bascule  towers  (Figs.  43-46-47)  are  the  chief  opportu- 
nity on  these  bridges  for  adornment.  Schwedler's  prize  design, 
made  in  1850  for  a  bridge  over  the  Rhine  at  Cologne,  had  a 


62 


ARTISTIC  BRIDGE  DESIGN 


double  bascule  at  the  center,  with  imposing  central  towers 
connected  with  an  overhead  footbridge,  similar  to  the  Tower 
bridge  at  London.  A  bridge  with  smaller  portal  tower,  over- 
loaded with  excessive  ornament,  may  be  seen  at  Camden, 
N.  J.,  the  tower  frame  being  covered  with  concrete  on  ex- 


Fig.   47 


panded  metal.  Portal  towers  and  arches  are  also  used  at  the 
ends  of  the  swing  bridge  over  Passaic  river  at  Fourth  street, 
Newark,  N.  J.,  the  iron  framing  being  covered  with  boards 
and  sheet  copper.  Besides  marking  the  limits  of  the  opening, 
these  features  are  useful  and  expressive,  and  serve  as  guard- 
houses and  shelters. 


ORDINARY  STEEL  STRUCTURES 


63 


The  position  of  the  trunnion  and  counterweight  greatly 
influences  the  appearance  of  bascule  bridges,  and  careful  study 
should  be  given  to  these  features.  In  the  Brayton  patent  the 
trunnions  are  elevated  to  avoid  the  need  of  counterweight 
pits,  and  the  presence  of  the  counterweight  is  emphasized.  On 
many  other  designs  the  counterweight  is  so  disposed  as  to  make 
any  aesthetic  treatment  almost  impossible. 

Swing  bridges  are  unsightly  and  the  part  above  the  pier 
has  no  meaning  or  use  when  the  bridge  is  closed,  unless  in  those 
where  the  dead  weight  is  at  all  times  transferred  to  the  center 


Fig.  48 


pier.  Reverse  curves  on  the  upper  chord,  and  portal  and 
tower  ornaments  or  finials  may  be  used  with  good  effect.  The 
full  benefit  of  swings  is  obtained  only  when  two  channels  are 
crossed  with  equal  arms.  Unequal  arms  of  either  truss  or 
plate  girder  fail  aesthetically  through  lack  of  symmetry,  and, 
including  the  counterweight  on  the  shorter  arm,  they  have 
excess  weight.  Reverse  curves  on  the  upper  chord,  such  as 
used  on  the  Third  avenue  and  Willis  avenue  bridges  at  New 
York,  and  at  Norwich,  England,  are  believed  by  some  to 
look  more  graceful  than  straight  lines  between  the  panel  points, 
but  they  need  a  greater  number  of  web  members,  and  the 
result  at  best  is  not  so  good  as  may  be  secured  from  some 
other  forms.     Continuous  segmental  curves  for  the  upper  chord 


64 


ARTISTIC  BRIDGE  DESIGN 


were  generally  used  on  the  early  timber  swings  in  America, 
such  as  shown  at  Webster  avenue,  Chicago  (Fig.  48).  Those 
at  New  London  and  Duluth  are  examples  of  swings  with 
upper  chord  points  on  a  curve,  and  straight  members  between, 
while  that  over  the  Connecticut  river  at  Middletown  (Fig,  49) , 
designed  by  the  writer  in  1 896,  has  upper  chords  in  a  straight 
line.  The  last  has  a  length  of  450  feet,  and  is  the  longest 
highway  swing  span  ever  built.*  Two  other  examples  of  the 
best  that  is  obtainable  in  through  swing  bridges,  are  the  Ship 


A«fl 

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it 

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'tm 

r^ 

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Fig.  49 

Canal  and  the  Seventh  avenue  swings  at  New  York,  the  only 
deserved  criticism  of  the  former  being  an  unfortunate  break  in 
the  upper  chord  at  the  second  panel  from  either  end.  The 
masonry  and  approaches  on  these  bridges  are  carried  out  with 
graceful  lines  and  fine  detail. 

The  tower  and  center  panel  of  swing  bridges  frequently 
contain  features  which  affect  their  appearance,  such  as  toggles 
at  the  upper  chord,  as  used  by  the  Erie  railroad  on  their  bridge 
at  Hammond.  The  tower  usually  contains  the  operator's 
house  and  platform,  and  as  the  house  is  conspicuous,  it  should 
be  made  an  architectural  study,  with  choice  detail,  and  it  can 
easily  be  made  attractive,  as  there  are  few  limitations.    The 

*  H.   G.   Tyrrell,   in  The  Engineer,  London,  March  1,  1901.     Railroad  Gazette 
Dee.   27,   1901. 


ORDINARY  STEEL  STRUCTURES  65 

center  tower  of  an  old  wooden  bridge  over  the  Arun  river  at 
Arundel  (1845)  might  well  be  used  as  a  model  by  some 
recent  designers.  The  appearance  of  swings  may  also  be  im- 
proved by  enclosing  the  turn-table  with  an  ornamental  cast-iron 
housing,  moulded  in  graceful  lines,  with  projecting  ring  courses, 
as  was  done  on  several  swings  in  England.  But  as  such  enclo- 
sures add  to  the  weight  and  cost,  and  make  mspection  more 
difficult,  they  are  not  favored  in  America. 

The  best  aesthetic  effect  in  swing  bridges  is  illustrated  by 
the  Lubeck  and  Libau  double  swings,  though,  like  other  double- 
leaf  bridges,  they  are  suitable  only  for  highways,  the  center 
connection  without  a  pier  being  too  uncertain  for  heavy  trains 
and  locomotives.  A  somewhat  similar  outline  with  a  single 
swing  between  adjoining  cantilevers,  has  a  good  appearance, 
but,  without  piers  under  the  ends,  is  subject  to  the  same  criti- 
cism as  those  at  Lubeck  and  Libau. 

Lift  bridges  of  the  South  Halsted  street  type,  with  towers 
at  each  side,  are  easily  made  attractive,  good  results  having 
been  obtained  by  W.  Moorsom  in  1850  in  his  design  for  a 
lift  bridge  over  the  Rhine  at  Cologne,  with  an  under-clearance 
of  1 04  feet,  and  by  Oscar  Roper  in  1 867  in  his  design  for  a 
lift  bridge  over  a  wide  river,  with  a  span  of  300  feet.  An 
elaborate  design  with  stone  towers  was  made  by  T.  E.  Laing 
(1873)  for  crossing  the  Tees  at  Middlesborough,  the  moving 
span  having  a  clear  width  of  200  feet  and  an  opening  for 
ships,  of  90  feet  beneath  it,  when  raised.  Five  years  later, 
M.  H.  Matthyssens  prepared  elaborate  designs  for  a  lift  bridge 
over  the  Scheldt  at  Antwerp,  the  central  moving  span  rising 
to  a  clear  height  of  130  feet  between  towers  131  feet  apart. 
A  still  more  elaborate  design  was  made  in  1883  by  J.  P. 
Bayley  for  a  lift  bridge  over  the  Thames  at  London,  the 
moving  portion  rising  between  a  pair  of  great  metal  arches, 
leaving  a  clear  passage  of  90  feet  for  ships  with  masts.  Many 
smaller  ones  were  designed  and  built  throughout  Europe,  in- 
cluding those  over  Grand  Surrey  canal  (1848),  Ourcq  canal 
(1868),  Rue  de  Crimee  (1886),  and  at  Dijon.     The  many 


66  ARTISTIC  BRIDGE  DESIGN 

designs  appearing  in  America  since  their  introduction  on  the 
Erie  canal,  include  those  at  Duluth,  Chicago,  Kansas  City, 
New  York,  Keithsburg  and  Portland.  Framed  towers  have 
the  best  appearance  when  the  rear  columns  have  either  a  straight 
taper  or  are  curved,  as  on  the  lift  over  Grand  Surrey  canal 
(1848),  The  connection  framing  between  the  tower  tops 
should  have  a  curved  lower  chord  in  the  form  of  a  flat  segment 
or  ellipse,  as  on  Moorsom's  design  of  1 850  for  Cologne. 

Transporter  or  Ferry  bridges  with  side  towers  and  a  plat- 
form at  great  height,  can  easily  be  made  beautiful  and  impres- 
sive, especially  when  the  center  span  is  borne  by  cables,  with 
their  graceful  curves.  The  moving  car  and  the  landing  plat- 
forms at  each  end  may  have  moderate  adornment  suitable  to 
their  location. 


CHAPTER  VIII 
Cantilever  Bridges 

Cantilever  bridges  are  a  modern  application  of  an  ancient 
principle.  Most  of  the  early  designs  contained  no  trace  of 
ornamental  features,  and  no  effort  was  made  to  beautify  them. 
Because  of  their  newness  they  were  said  to  be  a  difficult  type 
to  make  attractive,  an  excuse  which  has  since  proved  ground- 
less, as  some  recent  designs  are  among  the  most  artistic  ones 
ever  produced. 

The  proper  use  of  cantilever  bridges  was  at  first,  and  is 
still  often  misunderstood.  They  were  used  in  places  where 
no  scientific  reason  could  be  given  for  their  presence,  and  in 
many  cases  no  other  explanation  can  be  found  for  their  exist- 
ence than  to  provide  experience  for  their  designers. 

The  cantilever  or  bracket  bridge  has  merits  peculiarly  its 
own,  but  it  is  economical  only  when  erection  false  work  would 
be  very  difficult  or  impossible.  In  other  places,  with  easy  erec- 
tion, simple  spans  are  preferable,  for  they  are  stiffer  and  con- 
tain less  metal.  Structural  requirements  must  always  prevail, 
but  it  is  no  more  difficult  to  make  a  cantilever  attractive  than  a 
suspension  or  arch.  The  form  and  outline  should  indicate  the 
use  of  the  cantilever  principle.  In  this  respect  such  bridges 
as  the  Queensborough  (Fig.  51),  Borcea  and  Forth  (Fig. 
239)  are  a  success,  while  others,  like  the  Hooghly  cantilever 
(Fig.  52)  at  Calcutta,  have  a  wrong  outline  and  fail  to 
show  their  real  action. 

NUMBER  OF  SPANS 

The  three-span  cantilever,  like  that  at  Niagara,  is  the  best 
known  form,  the  two  anchor  arms  being  erected  on  false 
work,   and  the  main   span  built  out  to  meet  in  the  center. 

67    , 


68 


ARTISTIC  BRIDGE  DESIGN 


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CANTILEVER  BRIDGES 


69 


Bridges  of  this  type  have  horizontal  upper  chords  and  their 
outhne  shows  little  or  no  beauty.  Similar  ones  with  lower 
chords  horizontal  are  illustrated  by  the  bridge  at  St.  Johns, 
N.  B.  A  more  artistic  treatment  with  like  natural  conditions 
is  shown  in  Pont  de  la  Gryonne,  where  the  truss  depth  of  the 
side  spans  increases  gradually  from  the  abutments  to  the  piers, 
and  the  lower  chord  of  the  center  span  is  curved.  The  first 
artistic  cantilever  was  erected  in  1 884,  over  the  Danube  Canal 
at  Vienna,  and  three  years  later  the  Budapest  competition 
brought  out  several  fine  designs,  one  of  which  was  built. 


Cantilevers  with  many  spans  are  those  at  Cernavoda  (Fig. 
53),  Poughkeepsie  (Fig.  237)  and  Thebes,  all  of  which 
are  symmetrical,  and  in  contrast  to  these  are  the  unsymmet- 
rical  ones  over  the  Mississippi  at  Memphis,  the  Ohio  at  Mari- 
etta, and  the  East  river  at  New  York  (Fig.  51),  the  last 
being  unsymmetrical  in  respect  to  length  of  channel  openings. 


The  presence  of  a  central  suspended  span  has  been  given  as  a 
reason  for  lack  of  art  in  cantilever  bridges,  and  in  some  of 
them,  as  at  Blackwell's  Island,  this  element  has  been  omitted. 

CHORD  OUTLINE 

The  cantilever,  like  other  large  steel  bridges,  should  have  a 
graceful  outline  if  beauty  is  desired,  and  curved  chords  are 
preferable  artistically  to  straight  ones.  Curves  may  be  used 
for  either  one  or  both  chords,  as  conditions  will  allow.  The 
center  span  bottom  chord  may  be  made  a  segment  of  a  circle 


70 


ARTISTIC  BRIDGE  DESIGN 


and  the  bottom  chord  of  the  two  adjoining  anchor  spans  made 
to  correspond  with  the  middle  one,  as  in  the  Villefranche 
bridge  (Fig,  54),  which  is  one  of  the  finest  of  its  kind. 
Somewhat  similar  cantilevers  are  at  Budapest,  Mannheim, 
and  at  Highland  Park  in  Pittsburg,  though  the  last  lacks  the 


Fig.  54 


expensive  ornament  of  the  European  bridges.  The  lower 
chords  of  the  Forth  bridge  (Fig.  55)  are  segmental  curves  of 
great  radius  and  are  quite  satisfying,  but  the  end  approaches 
to  the  bridge  have  hardly  sufficient  dignity  to  harmonize  with 
the  rest. 


Chord  outlines  resembling  those  of  arches  and  suspensions 
are  best  suited  to  cantilevers  which  have  no  suspended  span,  for 
if  such  be  introduced,  the  continuous  curves  produce  a  less 
truss  depth  at  the  span  center  than  at  the  ends — the  reverse  of 
requirements.  The  bridge  over  the  Weser  at  Hameln  (Fig. 
56),   which  replaced  an  old  suspension,   was  made   of  the 


Fig.   56 

same  outline  as  its  predecessor,  but  a  similar  one  over  the  Dela- 
ware at  Easton  has  a  fifty-foot  center  span.  In  both  cases 
the  upper  chords  are  continuous  curves.  The  designers  of 
other  bridges,  like  the  Hassfurt  and  Posen  cantilevers,  have 
preferred   to   emphasize   the   construction   by   making   only   a 


CANTILEVER  BRIDGES 


71 


panel-point  connection  between  the  cantilever  arm  and  the 
adjoining  span,  a  method  which  is  well  illustrated  by  the 
Tolbiac  street  bridge  in  Paris  and  by  a  proposed  design  for  the 
Harlem  river  bridge  at  New  York.  (Fig.  60.)  But  contin- 
uous framing  is  preferable,  and  the  false  connecting  members 
between  the  adjoining  spans  add  stiffness  to  the  whole. 

Chords  may  also  be  curved  over  the  piers,  as  in  Mr.  Fidler's 
design  for  the  Quebec  bridge  (Fig.  50)  and  the  smaller 
Pines  bridge  at  Croton  Lake.  While  these  curved  lines  add 
to  the  general  appearance,  they  necessitate  extra  framing,  and 
straight  lines  above  the  pier  are  preferable.  Cantilever  trusses 
with  parallel  chords,  as  on  the  Dixville  and  Minneapolis 
bridges,  fail  to  represent  truthfully  the  stress  requirements  which 
need  the  greatest  depth  above  the  piers. 


Fig.   57 


Satisfactory  outlines  may  be  secured  by  locating  the  chord 
points  on  continuous  curves,  and  using  straight  members  between 
these  points.  Several  designs  for  the  Quebec  were  so  made, 
though  the  one  prepared  by  the  Board  of  Engineers,  and  the 
later  one  by  the  Dominion  Bridge  Company,  had  chords  in 
straight  lines.  In  both  of  the  latter  designs  the  question  of 
aesthetics  was  apparently  not  considered.  The  proposed  sys- 
tem of  K  web  bracing  in  the  last  design  is  its  first  important 
use  in  main  trusses,  though  it  has  previously  been  used  in  the 
lateral  system  of  several  bridges  in  Europe.  The  approaches 
in  Mr.  Fidler's  design,  with  heavy  masonry  arches  contrasting 
beautifully  with  another  type  of  construction  in  the  main  por- 


72 


ARTISTIC  BRIDGE  DESIGN 


tion,  are  much  superior  to  the  light  trestle  approaches  on  some 
of  the  later  plans.* 

Greater  stability  is  secured  by  sloping  the  truss  planes 
towards  each  other  at  the  top,  as  in  the  Forth  and  Cernavoda 
bridges,  and  whenever  the  cross  section  is  very  evident,  a  mod- 


Fig.  58 


erate  truss  inclination,  like  the  entasis  of  a  column,  will  prevent 
the  appearance  of  overbalance. 

Braced  towers  beneath  the  trusses  should  always  taper  in 
both  directions,   as  in  the  Niagara  bridge,  rather  than  stand 

♦  See  report  of  Mr.  Gustav  Lindenthal.  Engineering  News,  Nov.  16.  1911. 


CANTILEVER  BRIDGES 


72> 


vertical,  as  at  Verrugas  and  Pecos,  for  if  vertical,  they  have 
a  very  awkward  appearance. 

Cantilevers  of  the  Mingo  and  Beaver  type  have  become 
almost  standard  in  America.  The  lower  chord  is  horizontal 
for  the  platform  connections  and  the  upper  chords  curved  with 
the  greatest  truss  depth  above  the  piers  where  needed. 


Fig.  60 


Figs.  57,  58  and  59  are  designs  prepared  by  the  writer  for 
bridges  over  mountain  gorges  in  Western  America,  one  gorge 
having  a  depth  of  420  feet.  Fig.  59  somewhat  resembles  in 
principle  the  Sukkur  bridge  over  the  Indus  river  (Fig.  61  )  with 
a  span  of  820  feet.  (For  outlmes  of  many  other  cantilevers, 
see  Tyrrell's  "History  of  Bridge  Engineering.") 


Fig.  61 


ORNAMENT 

In  addition  to  the  usual  ornamental  features  at  the  balus- 
trade and  roadway,  the  portals  and  towers  offer  opportunity 
for  finial  decorations,  and  the  Forth  bridge  has  been  much 
criticized  because  of  the  absence  of  these  features. 

The  most  artistic  cantilevers  are  those  at  Budapest,  Mann- 
heim, Villefranche,  Highland  Park  and  Easton,  v/hile  others 


74 


ARTISTIC  BRIDGE  DESIGN 


in  which  art  is  utterly  absent  and  extreme  disregard  shown 
for  pleasing  outlines  are  those  at  Moline,  111.,  Muscatine  and 
Clinton,  la.,  Winona,  Minn.,  and  Lewiston,  Ida.  The  Alex- 
andria bridge   at   Ottawa,   Canada,    and   the   Beaver   bridge 


Fig.   62 


(Fig.  62)  are  in  the  cantilever  portion  excellent,  but  their 
symmetry  is  injured  by  the  presence  of  simple  truss  spans  at 
one  end  only. 


CHAPTER  IX 

Metal  Arches 

Metal  arches  should  exhibit  a  character  of  their  own,  and 
should  differ  from,  rather  than  resemble  masonry  arches.  They 
contain  three  essential  parts:  (1)  the  platform,  (2)  the  plat- 
form supports  or  spandrel  framing,  and  (3)  the  arch  ring. 

THE  DECK 

The  deck  should  be  arranged  symmetrically  with  space  for 
cars,  vehicles  and  pedestrians.  The  appearance  of  bridges 
which  are  otherwise  attractive  has  been  spoiled  by  placing  car 
tracks  with  open  timber  floor  off  to  one  side.  Where  there 
are  two  decks,  the  lower  one  is  best  suited  for  tracks  and  the 
upper  one,  with  unobstructed  view,  for  vehicles  and  pedes- 
trians, this  arrangement  being  also  the  most  economical.  Half 
through  deck  construction  is  suitable  for  railroad  bridges,  the 
side  girders  forming  a  safeguard  in  case  of  derailment,  an  idea 
which  was  carried  out  on  the  Garabit  arch.  A  decided  road- 
way camber  is  not  only  useful  for  drainage,  but  adds  grace  to 
the  whole. 

SPANDREL  FRAMING 

Floor  supports  or  spandrel  framing  of  arches  are  similar  to 
viaduct  or  trestle  bents,  and  are  similarly  proportioned,  the 
economic  distance  between  columns  depending  on  the  height 
from  arch  to  floor.  But  as  too  many  members  cause  confusion, 
a  few  large  bents  are  artistically  preferable  to  a  greater  num- 
ber of  smaller  ones,  and  several  of  the  largest  arches  are  made 
in  this  way,  with  only  three  to  six  bents  or  towers  supporting 
the  roadway  girders.  Economy  is  secured  when  flat  arches 
with  small  rise  have  a  greater  number  of  spandrel  columns,  but 

75 


76 


ARTISTIC  BRIDGE  DESIGN 


arches  with  great  rise  should  have  those  supports  further  apart. 
If  braced  piers  are  used  in  the  spandrels  to  support  the  deck, 
they  should  preferably  taper  in  four  directions,  and  correspond 
in  outline  and  detail  with  similar  parts,  if  any,  in  the 
approaches.  When  the  end  bents  support  part  of  an  approach 
span  in  addition  to  a  floor  panel  above  the  arch,  the  bent  should 
then  be  double,  or  at  least  appear  larger  and  stronger  than 
the  regular  ones  (Fig.  63).    The  end  bents  of  spandrel  braced 


Fig.  63 


arches  with  approach  spans  should  have  sufficient  prominence 
to  mark  the  limits  of  the  central  opening,  and  they  should  be 
indicated  above  the  roadway  by  a  conspicuous  feature.  A 
good  effect  may  be  secured  by  a  series  of  small  cast  iron  span- 
drel arches  just  below  the  floor  cornice,  an  arrangement  which 
appeared  on  the  prize  designs  for  the  Washington  bridge  over 
the  Harlem  river  at  New  York.  Where  the  crown  depth 
of  a  spandrel  braced  arch  is  small,  web  plates  may  be  used 
for  a  short  distance  each  side  of  the  center,  as  in  the  Cedar 
avenue  bridge  at  Baltimore.  Tapering  compression  members 
with  greater  center  than  end  widths,  as  in  the  Viaur  via- 
duct, are  not  artistic  and  are  rarely  economical;  parallel  ones 
are  preferable.  An  objection  to  numerous  light  spandrel 
bents  is  that  the  slender  columns  need  supporting  at  one  or 
more  intermediate  points,  but  the  condition  may  be  remedied 
by  using  a  smaller  number  of  heavier  bents  or  towers.  Many 
old  cast  iron  arches,  as  the  St.  Peters  bridge  at  Paris,  had  a 
series  of  iron  circles  in  the  spandrels,  but  circular  forms  are  not 
the  best  for  sustaining  weight,  and  the  aesthetic  effect  was  not 
satisfactory.  A  shield  on  the  center  pier  of  the  cast  iron  arch 
at  Chestnut  street,  Philadelphia,  bears  the  date  of  construction. 


METAL  ARCHES  77 

RELATIVE  POSITION  OF  DECK  AND  SPRINGS 

The  relative  elevations  of  roadway  and  springs  give  to 
metal  arches  their  chief  character.  Individuality  is  best  exhib- 
ited when  a  form  is  selected  which  is  impossible  in  masonry, 
and  for  this  reason  through  or  partly  through  metal  arches  are 


Fig.   64 


often  preferred,  like  those  at  GriinenthaP  (Fig.  64)  and 
Straubing,  the  crescent  shape  contrasting  with  stone  arches  and 
revealing  the  special  character  of  steel. 

ARCH  TYPES 

The  three  common  arch  types  are  ( 1  )  plate  girder  ribs, 
(2)  spandrel  lattice,  and  (3)  curved  lattice  ribs.  Plate  girder 
arches  are  illustrated  by  the  Washington  bridge  at  New 
York,  the  Forbes  street  bridge  at  Pittsburg,  and  the  Con- 
stance-Baden bridge  in  Switzerland.  The  Harvard  bridge 
at  Boston,  made  to  imitate  an  arch,  is  really  a  plate  girder 
curved  on  the  under  side.  The  Manhattan  Valley  viaduct 
in  New  Yprk,  with  twenty-four  semicircular  sixty-five-foot 
arches,  is  not  economical,  the  form  being  adopted  for  its  bet- 
ter appearance.  Small  plate  girder  arches  may  be  curved  on 
the  under  side  only,  with  upper  side  on  three  or  more  straight 
lines,   as  on  the  Constance-Baden  bridge. 

Spandrel  braced  arches  are  illustrated  by  the  Niagara  rail- 
road bridge  (Fig.  65),*  and  the  Lake  street  bridge  at  Minne- 

*Prom   "History  of  Bridge  Engineering,"  by  H.   G.  Tyrrell. 


78 


ARTISTIC  BRIDGE  DESIGN 


apolis,  and  the  Salmon  river  bridge  in  British  Columbia  (Fig. 
66).  The  action  or  purpose  of  this  type  is  not  so  evident  as 
with  curved  girder  or  lattice  ribs  and,  sincerity  or  truthful 
expression  being  an  essential  of  good  design,  spandrel  braced 


Fig.  63 


arches  are  not  so  desirable  as  other  forms.  Care  should  be 
taken  to  secure  effective  angles  of  inclination  for  the  web 
members.     The  truss  depth  and  panel  length   at  the  center 


Fig.  66 


should  be  such  that  diagonals  will  not  have  too  flat  an  angle, 
and  those  near  the  ends  may  cross  two  panels  with  sub-trussing 
at  the  middle  (Fig.  67),  as  in  the  Minneapolis  bridge,  which 
is  preferable  in  this  respect  to  the  one  at  Niagara. 


METAL  ARCHES 


79 


Lattice  rib  arches  are  either  deck  or  through,  the  latter 
type  being  used  chiefly  in  Europe,  and  none  of  these  forms 
are  suitable  for  spans  much  less  than  300  feet.  The  Coblenz 
bridge  of  1864  (Fig.  225),  which  was  the  first  important 
wrought-iron  arch,  was  a  deck  bridge,  as  also  are  the  two 
metal  arch  designs  (Figs.  217-218)  for  the  proposed  Hudson 
memorial  bridge  at  New  York,  which  are  among  the  finest 


designs  of  the  kind  ever  produced.  Through  arches  are  illus- 
trated by  those  at  Bonn  (Fig.  68),  over  the  Rhine,  and  at 
Magdeburg,  over  the  Elbe.  The  Bonn  bridge  has  true  arches 
with  inclined  pier  thrusts,  but  those  at  Magdeburg,  Mainz  and 
Worms,  though  of  similar  outline,  have  tension  members 
beneath  the  floor  to  resist  the  arch  thrust,  and  the  pier  reactions 
are  vertical.  They  are  known  as  "braced  tied  arches."  The 
Mainz  bridge  (Fig.  230)  is  somewhat  injured  by  the  pres- 
ence of  hand  railing  on  the  upper  chords,  which  detracts  from 
its  dignity.  The  Worms  bridge  (Fig.  227)  has  magnificent 
stone  portal  towers  adorned  with  figures  of  lions  and  clocks  over 
the  roadway — a  very  appropriate  feature.  Through  arches 
have  an  artistic  outline,  and  as  the  trussing  adjoins  the  upper 
chord,  and  the  web  contains  vertical  hangers  only,  there  is  little 
framing  to  obstruct  the  river  view.  The  appearance  is  further 
improved  in  some  bridges,  as  at  Bonn,  by  bending  the  chord 
sections  to  a  uniform  curve,  though  the  expedient  necessitates  an 
increase  in  chord  section  of  about  twenty  per  cent.     Curved 


80 


ARTISTIC  BRIDGE  DESIGN 


— t. 


-    ^ 


S|   ! 


i  i 


METAL  ARCHES 


81 


arch  ribs  are  well  suited  for  ornamental  foot  bridges  over  canals 
or  railroad  tracks,  and  have  also  been  used  in  spans  of  great 
length,  such  as  the  Eads  bridge  at  St.  Louis  and  the  proposed 
ones  over  the  St.  Lawrence  river  at  Montreal  and  the  North 
river  at  New  York,  with  spans  of  1 ,000  to  3,000  feet.  Mr. 
Charles  Steiner's  design  for  one  at  Montreal  with  a  central 
span  of  1,250  feet,  is  shown  in  Fig.  71.     The  span  arrange- 


ment on  the  Dusseldorf  bridge  (Fig.  69)  over  the  Rhine,  is 
hardly  as  satisfactory  as  that  at  Bonn  (Fig.  68),  for  the  latter 
has  a  large  central  arch  with  a  smaller  one  at  each  side,  making 
the  bridge  nearly  symmetrical. 


PINS  OR  HINGES 

The  form  of  arch  depends  chiefly  on  the  bearings,  which 
may  have  either  three,  two  or  no  hinges.  The  three-hinged 
arch,  with  joints  at  the  ends  and  center,  must  be  stiff  between 
these  points,  but  may  taper  to  a  small  depth  at  the  bearings. 
An  excellent  and  expressive  example  of  the  three-hinged  bridge 
is  the  recent  one  at  Yunnan,  China,  which  is  simply  a  triangular 
frame  supporting  the  deck  at  the  center  and  the  two  quarter 
points.  The  Alexander  III.  bridge  at  Paris  is  probably  the 
most  beautiful  example  of  a  three-hinged  arch  (Fig.  72), 
though  its  small  rise  causes  it  to  lack  the  appearance  of  strength, 
which  is  so  essential  to  good  design. 

Two-hinged  arches  are  illustrated  by  the  Pia  Maria  at 
Oporto,  and  the  Garabit   (Fig.   73),  Griinenthal,  Bonn  and 


82 


ARTISTIC  BRIDGE  DESIGN 


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METAL  ARCHES  83 

Niagara-Clifton  (Fig.  80)  arches.  These  are  stiff er  and  have 
a  finer  appearance  than  those  with  three  hinges.  The  lattice 
ribs  may  either  have  parallel  chords,  as  at  Niagara-Clifton,  or 
may  taper  from  the  required  center  depth  to  the  end  pins,  as  in 
Garabit  and  Griinenthal,  though  any  of  these  forms  truthfully 
show  the  stress  conditions. 


iij'<M:^N&js<E>a.^i><&3xi><^^ 


Pig.   73 


Bridges  with  no  hinges  have  the  best  appearance  and 
require  the  least  material,  but  there  is  often  difficulty  in  realizing 
the  assumed  bearings.  They  have  frequently  been  erected  at 
first   on   end  hinges,   as  at  Coblenz    (Fig.   225),    and   after 


Fig.   74 


completion  the  ends  wedged  up  solid  against  their  bearings. 
Square-ended  arches  should  increase  in  depth  from  the  center 
to  the  springs  similar  to  masonry  arches,  as  in  the  Luiz  I  arch 
at  Oporto  and  the  Mungsten  bridge  (Fig.  74) . 


84  ARTISTIC  BRIDGE  DESIGN 

ARCH  FORMS 

In  comparing  spandrel  braced  arches  with  plate  and  lat- 
tice ribs,  the  last  are  by  far  the  best  appearing,  especially  for 
long  spans.  Circular  segments,  parabolas  or  hyperbolas  have 
all  been  used,  and  any  of  them  are  suitable  for  arches  of  small 
rise,  though  for  a  condition  approaching  uniform  loading,  the 
parabola  is  nearest  to  the  line  of  pressure.  Circular  segments 
are  more  easily  drawn  and  they  never  fail  to  satisfy  the  eye. 
Parabolic  arches  of  large  span  and  rise,  like  the  Garabit  and 
Mungsten  bridges   (Figs.  73-74),  though  structurally  correct 


fe^^AN 


are  not  artistic.  Hyperbolic  arches,  as  in  the  Menominee 
bridge,  have  nothing  to  recommend  them,  and  a  straight  trian- 
gular form  is  preferable.  The  triangular  arch  is  indeed  often 
a  more  truthful  representation  of  the  constructive  principles 
involved,  and  for  this  reason  they  are  a  delight.  Mystery  and 
deception,  so  often  carried  out  in  construction,  should  be  eradi- 
cated. Simple  forms  are  preferable  to  complex,  especially 
when  they  are  more  sincere.  The  beauty  of  the  Yunnan 
arch  (Fig.  75)  lies  in  its  simplicity — its  purpose  is  so  evident — 
and  the  same  is  true  of  the  new  Thermopylae  arch  (Fig.  76)  in 
Greece.  Even  the  triangular  railroad  arch  over  an  Alaskan 
gorge,  wholly  of  straight  lines,  is  preferable  in  some  respects 
to  others  in  which  the  action  is  obscured  or  concealed.  Arches 
made  with  double  lenticular  trusses  meeting  at  the  crown 
hinge,  Hke  the  500-foot  spans  proposed  by  Mr.  Eads  for  the 
St.  Louis  bridge,  are  not  artistic,  though  perhaps  economical. 


METAL  ARCHES 


85 


Curved  ribs  with  parallel  chords  have  a  better  appearance 
than  any  other  form.  Alternate  web  members  of  the  lattice 
ribs  should  be  vertical  for  convenience  of  connections,  though 
they  are  otherwise  arranged  in  the  Eads  bridge,  and  two  pro- 
posed designs  for  the  Harlem  river,  the  latter  having  web  posts 
normal  to  the  chords.  Lattice  ribs  with  the  lower  chord  curved, 
and  the  upper  one  in  three  straight  lines,  as  in  the  Brooklyn- 


SradeZi  , 

Taral  Lenqth  584.25  ■ 

■  S4Ar-  — --sp- 


—  -  #♦.■«' >p-/«/Z'->j 


Fig.  76 


Brighton  viaduct,  are  not  so  attractive  as  parallel  curves,  though 
the  cost  of  bending  is  partly  avoided.  Some  designers  have 
even  curved  the  sections  between  the  panel  points  at  an 
increased  cost,  in  order  to  make  a  perfect  outline.  The  same 
kind  of  web  should  be  maintained  throughout,  rather  than  a 
combination  of  plate  and  open  lattice,  as  in  the  Riverside  arch 


at  Cleveland.  Plates  are  necessary  and  permissible  at  the  ends, 
but  should  appear  as  minor  features  and  not  extend  out  to  the 
quarter  points. 

Unsymmetrical  arches  are  correct  and  acceptable  when 
used  for  approach  spans  where  the  rising  hillside  necessitates 
a  higher  spring  at  the  abutments  than  at  the  intermediate  piers 
in  the  valley.     But  the  semi-arch  of  the  unsymmetrical  span 


86 


ARTISTIC  BRIDGE  DESIGN 


should  be  of  the  same  form  as  the  adjoining  valley  arch,  as  in 
the  St.  Sylvestre  bridge,  Switzerland.  A  violation  of  this 
requirement  is  found  in  the  Rio  Grande  cantilever  arch  in  Costa 
Rica,  where  no  harmony  is  seen  between  the  approach  and 
center  outline.  The  finest  cantilever  arch  ever  executed  is  the 
Viaur  viaduct  in  France,  though  a  similar  one  (Fig.  77)  was 
proposed  the  same  year  to  carry  Massachusetts  avenue  over 
Rock  Creek  at  Washington.  A  very  beautiful  small  one 
crosses  the  Eibe-Trave  canal  at  Molln,  and  another  (Fig.  78) 
may  be  seen  in  Lincoln  Park,  Chicago. 


Fig.  7! 


Springs  should  be  at  different  elevations  when  the  deck  is 
on  a  very  noticeable  grade,  the  difference  in  their  height  cor- 
responding with  the  floor  grade,  as  in  the  Kornhaus  bridge 
(Fig.  231  ).  A  difficult  mountain  site  may  naturally  place  the 
springs  at  different  elevations,  as  in  the  Surprise  Creek  bridge, 
though  wherever  possible  lack  of  symmetry  should  be  avoided. 
Further  study  of  the  site  might  show  that  a  small  change  of 
outline,  span  length  or  position  would  result  in  level  springs  and 
equal  end  heights. 


METAL  ARCHES 


87 


Arches  should  have  sufficient  rise  to  display  their  strength, 
as  in  the  Stony  Creek  bridge  (Fig.  79) ,  which  crosses  the  gorge 
in  a  single  span.  When  too  flat,  the  arch  appears  like  a  lattice 
girder,  and  its  true  action  is  not  sufficiently  evident.  A  large 
relative  rise  is,  in  fact,  one  of  the  chief  beauties  of  the  arch,  and 
many  w^hich  are  otherwise  imposing,  fail  by  insufficient  rise,  to 
display  their  strength  and  security.     When  an  arch  contains 


Fig.  79 


only  two  ribs,  strength  is  shown  by  placing  them  in  sloping 
planes  further  apart  at  the  shoes  than  at  the  platform.  The 
roadway  trusses  above  the  arch  may  stand  vertical,  as  in  the 
Paderno  bridge,  which  has  double  decks. 


PIERS  OR  TOWERS 

Masonry  towers  between  adjoming  spans  should  continue 
up  to  or  above  the  roadway  for  the  best  effect.  In  this  respect 
the  Washington  bridge  is  superior  to  either  the  Main  street 
bridge  at  Minneapolis  or  the  Kirchenfeld  bridge,  which  have 
metal  towers.  The  piers  of  the  Hell  Gate  arch  (Frontispiece) 
were  to  be  of  red  granite  concrete  on  gray  granite  base. 
Metal  piers  when  used  in  spandrels  or  approaches  should  have 
a  slight  taper  in  two  directions,  like  the  trunks  of  trees,  rather 
than  standing  vertical,  but  the  taper  must  be  small  or  the 
appearance  will  not  be  improved.  The  general  style  of  bracing 
on  all  the  piers  should  be  uniform  instead  of  changing,  as  in 
the  Mungsten  bridge.  Piers  which  resist  the  thrust  of  approach 
arches,  as  in  the  Kornhaus  and  the  old  Coalbrookdale  bridges, 
must  be  proportioned  for  their  stresses,  and  should  appear  to 
have  sufficient  strength.     When  insufficient  construction  funds 


88  ARTISTIC  BRIDGE  DESIGN 

are  available  at  first,  stone  piers  may  be  erected  complete  and 
temporary  timber  arches  placed  between  them,  to  be  replaced 
with  steel  or  masonry  when  the  timber  has  served  its  temporary 
purpose. 

APPROACHES 

Symmetry  is  the  principal  requisite  for  artistic  approaches. 
When  the  sides  of  a  valley  rise  at  different  inclinations,  an 
approach  should  first  be  designed  for  the  shorter  end,  and 
the  nearest  possible  reproduction  made  of  it  on  the  other  or 
longer  end.  The  remaining  part  of  the  longer  approach  should 
then  be  carried  out  in  a  different  type  of  construction,  divided 
from  the  symmetrical  part  by  some  prominent  feature.  This 
expedient  separates  the  central  part  from  the  rest,  and  shows 
that  natural  disadvantages  have  been  overcome.  Open  arch 
approaches  are  more  artistic  than  heavy  retaining  walls  with 
solid  filling  which  have  a  massive  appearance,  but  abutments 
should  correspond  with  the  main  bridge,  and  heavy  plate  arches, 
as  in  the  Manhattan  Valley  viaduct,  need  heavy  abutments. 

Large  metal  arches  with  masonry  approaches  should  have 
towers  or  other  forms  above  the  deck  dividmg  one  kmd  of  con- 
struction from  the  other.  The  finest  single  arch  designs  are 
those  (Figs.  217-218)  for  the  proposed  Hudson  Memorial 
bridge,  and  if  any  criticism  of  them  were  possible,  it  is  that 
since  a  steel  arch  was  imperative  for  the  center  span,  metal 
might  have  been  more  appropriate  for  the  approaches.  One  of 
these  designs  showed  curved  extensions  in  the  end  retaining 
walls,  forming  retreats  which  were  covered  with  shelters  and 
provided  with  seats,  a  most  appropriate  utility  on  a  large  bridge. 
The  position  of  these  shelters  was  further  indicated  by  four 
columns  at  each  end.  The  beauty  of  the  world's  greatest 
arch  (Fig.  80)  has  unfortunately  been  marred  by  the  entrance 
spans,  which  have  no  conformity  with  the  central  one.  The 
form  is  said  to  have  resulted  from  a  desire  to  leave  the  view 
of  Niagara  Falls  unobstructed.  A  wide  plaza  at  the  terminus, 
as  on   the   Riverside   viaduct.    New   York,   might   be   partly 


METAL  ARCHES 


89 


occupied  by  a  monument  or  statue,  and  shafts  or  columns  might 
bear  inscription  plates  as  on  the  Garibaldi  bridge  at  Rome, 
which  give  the  dates  of  Garibaldi's  victories. 


Fig.   80 


ORNAMENT 


The  principal  and  almost  the  only  ornament  ordinarily 
applied  to  metal  arches  is  a  fascia  of  cast  iron.  Elegance  may 
be  displayed  in  pylons,  columns,  statuary  and  lamp  clusters 
as  on  the  Alexander  III  (Figs.  72-226),  or  the  entrance 
bridge  at  the  Pan-American  Exposition.  The  proper  place  for 
features  on  the  deck  is  above  the  piers  rather  than  at  the  span 
center,  though  the  latter  position  may  be  appropriate  to  mark 
the  middle  of  a  long  bridge  or  series  of  spans.  Triumphal 
roadway  arches  were  extensively  used  on  old  Roman  bridges, 
and  new  decorative  forms  have  been  devised  on  some  recent 
designs  like  the  proposed  memorial  bridge  at  Washington. 


HELL  GATE  ARCH 

The  proposed  Hell  Gate  arch  of  1 ,000  ft.  is  one  of  the 
largest  ever  projected.  It  is  part  of  a  prospective  viaduct 
three  miles  in  length,  connecting  the  Pennsylvania  railroad 
with  the  New  York,  New  Haven  &  Hartford  railroad,  from 
the  mainland  to  Ward's  Island.  Provision  was  made  on  the 
plans  for  four  tracks  on  a  stone  ballast  deck  1 40  ft.  above  the 
water,  while  the  arch  crown  would  rise  to  a  height  of  300 
ft.  The  towers  are  shown  in  red  granite  concrete  on  grey 
granite  bases,  and  the  total  estimated  weight  of  steel  in  the 
whole  viaduct  is  80,000  tons.  The  design  is  the  work  of 
Gustav  Lindenthal,  engineer,  and  Palmer  and  Hornbostel, 
architects.      (See  Frontispiece.) 


CHAPTER  X 
Suspension  Bridges 

The  suspension  is  one  of  the  easiest  types  to  beautify,  and 
it  can  hardly  fail  to  be  attractive  unless  through  deliberate  pur- 
pose or  utter  negligence,  for  the  cables  naturally  assume  a 
perfect  curve.  The  floor  is  often  given  an  upward  rise  or  road- 
way camber,  which  is  evident  by  day  and  outlined  by  lights 
along  the  deck  at  night.  From  the  very  nature  of  the  types, 
the  best  and  most  truthful  appearance  is  obtained  when  the 
floor  is  hung  below  the  cables  of  suspension  bridges,  and 
mounted  on  walls  or  columns  above  an  arch. 

Suspension  bridges  are  among  the  very  oldest  forms,  but 
previous  to  1  796  the  cables  were  drawn  taut  and  the  floor  laid 
directly  thereon.  It  was  not  till  after  the  introduction  of  level 
platforms  suspended  from  the  cables  that  they  came  greatly  into 
favor,  and  then  for  half  a  century  many  of  the  finest  bridges 
were  suspensions.  They  are  suitable  only  when  the  imposed 
loads  are  so  small  in  comparison  with  the  weight  of  the  bridge 
that  the  live  load  will  cause  no  change  in  the  curvature  of  the 
cable.  Suspension  bridges  are  serviceable  in  small  spans  for 
pedestrian  travel,  or  other  light  loads,  and  are  economical  for 
extremely  heavy  bridges  such  as  those  at  New  York,  where 
the  weight  of  several  trains  is  small  in  proportion  to  the  weight 
of  the  bridge  itself.  They  contain  less  metal  than  truss  bridges 
but  frequently  cost  more.  The  great  suspensions  at  New 
York,  costing  twenty  to  thirty  millions  each,  are  the  most 
prominent  objects  about  the  city,  and  have  never  been  equalled 
in  carrying  capacity,  though  designs  have  been  made  for  much 
longer  spans,  including  one  by  the  eminent  engineer,  M.  Oudry, 
with  four  spans  of  1 ,000  meters  each   to  cross  Messina  straits. 

90 


SUSPENSION  BRIDGES 


91 


TYPES 

Suspension  bridges  are  of  the  Roebling,  Ordish,  Dredge  or 
discard  type,  the  first  being  the  common  and  almost  only 
kind  in  America.  The  ftoor  in  the  Ordish  bridge  (Fig.  81  )  is 
supported  by  straight  tension  members  from  the  panel  points  of 
the  roadway  to  the  tower  tops,  the  tension  bars  being  sup- 


n 


Fig.  81 


n 


ported  by  a  curved  cable  above  them,  the  only  purpose  of 
which  is  to  carry  the  working  members.  The  type  is  illustrated 
by  the  Albert  bridge  at  London,  and  two  bridges  over  the 
Moldau  at  Prague.  In  the  Dredge  type  (Fig.  82)  cables  from 
the  towers  support  the  whole  weight,  but  the  suspenders  from 
the  cables  incline  from  the  floor  towards  the  towers,  instead  of 


Fig.  82 


hanging  vertical.  A  bridge  of  this  description  was  erected  over 
the  Spey.  The  discard  bridge  has  numerous  tension  mem- 
bers radiating  from  the  towers,  and  the  type  is  extensively  used 
m  France,  and  many  designed  by  French  engineers  have  been 
exported  to  other  countries. 

Schwedler's  design  for  a  bridge  over  the  Rhine  at  Cologne 
(1 850)  may  be  called  a  type,  for  it  contained  two  side  suspen- 
sion spans  and  a  pair  of  very  handsome  center  towers,  with  a 
double  bascule  span  between  them.  A  similar  design 
was  adopted  for  the  Tower  bridge  at  London,  though  with 
very  different  architectural  treatment.  In  these  designs  the 
tension  on  the  towers  from  the  cables  of  the  side  spans  is 
resisted  by  members  between  the  towers  above  the  channel.  In 
the  Tower  bridge  (Fig.  83)  these  ties  are  concealed  by  two 


92 


ARTISTIC  BRIDGE  DESIGN 


high  level  foot  walks  reached  by  elevators,  but  the  foot  walks 
and  concealed  tension  bars  fail  to  exhibit  their  real  purpose, 
and  in  this  respect  the  design  is  faulty.      The   architectural 


treatment  of  the  towers  has  been  severely  criticized  by  English 
architects,  who  declare  that  the  stone  facing,  which  is  noth- 
ing more  than  an  enclosure  for  the  metal  which  sustains  the 


loads,  is  a  false  representation  and  made  to  appear  like  a  struc- 
tural part  of  the  bridge.  The  horizontal  belt  courses  on  the 
towers  also  produce  a  diminutive  effect,  and  the  central  ones 
should  have  been  omitted. 


SUSPENSION  BRIDGES  93 

The  towers  of  the  Cubzac  bridge  (Fig.  84)  over  the 
Dordogne  (1839),  with  five  spans,  were  braced  together  with 
diagonal  ties  above  the  cables,  but  the  presence  of  the  ties 
greatly  injured  its  appearance. 

NUMBER  OF  SPANS 

The  aesthetic  appearance  of  bridges  is  greatly  influenced  by 
the  number  of  spans.  Suspension  bridges  generally  have  two 
towers,  but  they  have  been  erected  with  only  a  single  one, 
as  at  Gotha  and  Prague,  or  with  many  towers,  like  the  old 
Smithfield  street  bridge  at  Pittsburg.  The  Seventh  street  at 
Pittsburg,  the  Lehigh  river  bridge  at  Easton*  and  the  Lambeth 
bridge  at  London  each  had  three  towers,  while  the  Newbury- 
port  bridge  had  four  and  the  Nicholas  bridge  over  the  Dnieper 
had  five. 

TOWERS 

When  the  foundation  is  in  water  the  piers  are  usually  sepa- 
rate from  the  towers,  though  when  both  are  masonry,  the 
latter  are  merely  an  extension  of  the  piers.  The  purpose  of 
eaeh  is,  however,  quite  different,  and  they  should  receive 
different  and  individual  treatment.  Piers  when  in  water  should 
have  pointed  ends  up  to  or  above  high  water  level,  and  in 
rapid  northern  rivers  they  may  require  ice  breakers.  They  must 
be  structurally  sufficient  to  sustain  the  loads  and  any  elements 
are  appropriate  which  emphasize  strength,  such  as  deep  stone 
courses,  projecting  footings,  and  rough  stone  face.  Cut  waters 
on  both  ends  are  a  necessity  in  tidal  channels  with  alternate 
currents  in  both  directions,  and  in  any  case  they  prevent  scour 
and  make  the  pier  more  graceful  and  symmetrical,  as  is  well 
illustrated  in  the  old  suspension  bridge  at  Budapest  (Fig.  234) . 
When  not  in  water  the  piers  may  be  rectangular  masonry  pil- 
lars either  separate  or  connected  beneath  the  roadway  by  arches, 
as  in  the  Jefferson  Street  bridge  at  St.   Louis.      If  cylinder 

*  H.  G.  Tyrrell,  in  The  Engineer,  London,  Sept.  20,  1901.     Scientiflc  American 
Supplement,    Sept.    28,   1901.      Engineering   News,   Nov.    22.    1900. 


94 


ARTISTIC  BRIDGE  DESIGN 


piers  are  adopted,  the  appearance  should  and  can  easily  be 
made  more  pleasing  than  in  the  Lambeth  suspension  at  London. 
Bridges  have  occasionally  been  made  with  only  one  cen- 
tral tower,  as  in  the  foot-bridge  at  Prague  which  supported 
two  adjoining  spans  of  1  58  feet,  but  two  or  more  are  the  usual 
custom.  They  must  first  fulfill  their  structural  requirements, 
which  is  to  form  a  support  for  the  cables,  without  obstructing 
the  road  and  walks,  but  when  this  is 
accomplished  the  next  resquisite  is 
adornment.  Towers  are  so  prominent 
from  any  point  of  view  that  plain  con- 
struction without  beauty  is  inexcusable, 
for  the  additional  cost  of  such  work  is 
small  in  comparison  with  the  whole  out- 
lay. The  difference  in  effect  is  easily 
seen  by  comparing  the  beautiful  ones 
of  the  Budapest,  Fribourg,  Chelsea, 
St.  Louis  or  Tower  (Fig.  83)  bridges, 
with  the  simple  structural  towers  of  the 
Brooklyn  (Fig.  235),  Williamsburg 
(Fig.  85)  or  Lambeth  bridges.  It 
may  be  noted  that  the  beautiful  Buda- 
pest bridge  in  Austria  (Fig.  234)  is 
the  work  of  the  eminent  Irish  engineer  W.  Tierney  Clark,  who 
after  completing  it  placed  at  each  end  a  pair  of  British  lions. 

Towers  have  been  made  of  stone,  cast  iron,  steel  and  wood, 
all  the  early  ones  being  of  the  first  two  materials.  Cast  iron 
has  the  merit  of  lending  itself  readily  to  ornamental  treatment, 
and  many  of  the  early  bridges,  as  those  at  Seraing,  Chelsea  and 
several  in  Pittsburg,  including  Roebling's  eight-span  bridge  at 
Smithfield  street  ( 1 845  )  were  thus  constructed.  When  treated 
with  true  mdividuality,  cast-iron  towers  were  often  artistically 
satisfactory,  but  the  iron  should  not  be  made  to  represent  stone 
or  any  other  material  than  itself,  as  was  done  in  the  piers  of 
the  ill-fated  Tay  bridge. 

The  beauty  of  masonry  towers  depends  on  general  outline 


Elevation  of  Tower 
Fig.   85 


SUSPENSION  BRIDGES 


95 


and  proportion,  and  also  on  detail,  two  fine  examples  being 
those  in  the  old  Hammersmith  bridge  at  London  and  the 
Budapest  bridge  of  1845.  Other  excellent  stone  ones  are 
in  the  Lorient  bridge  of  1847  and  the  Nicholas  suspension  over 
the  Dnieper.  Towers  should  appear  to  support  their  cables 
with  easy  grace.     Statuary,  frieze  courses,  or  smaller  features. 


Fig.   86 


such  as  fountains,  are  appropriate.  As  they  occupy  the  usual 
sidewalk  space,  the  footways  may  be  curved  out  around  them 
and  supported  by  structural  members  from  the  piers.  When 
the  piers  or  towers  support  land  arches  in  addition  to  the  cables, 
as  on  the  Menai  and  Roche  Bernard  bridges  (Fig.  86)  they 
must  be  heavy  enough  to  resist  the  combined  stresses.  Hie 
Menai  piers,  though  hollow,  are  very  heavy  and  substantial, 
corresponding  with  the  other  work  of  Mr.  Telford. 


^^IV^r^^T^/^«^fvf 


Figr.  8-i 


The  towers  of  many  suspension  bridges  in  America,  such 
as  those  at  Montmorency  Falls,  Charleston  and  Elizabethtown, 
consist  of  single  disconnected  tapering  masonry  shafts,  with 
appropriate  caps  and  bases.  In  rustic  surroundings  or  parks, 
different  treatment  may  occasionally  be  appropriate,  as  in  the 
recreation  park  in  Paris,  where  the  towers  of  a  suspension 
bridge  are  of  natural  rock  with  a  roadway  cut  between  them. 
The  supports  for  a  suspension  bridge  at  Oak  Park,  111.,  con- 
sisted of  natural  growing  trees  on  each  side  of  the  river. 


96 


ARTISTIC  BRIDGE  DESIGN 


I 


S— sf- 


SUSPENSION  BRIDGES  97 

Steel  towers  are  the  newest  form,  and  are  well  illustrated 
by  the  two  latest  suspensions  over  the  East  River,  and  in  the 
proposed  one  over  the  North  River  at  New  York.  They 
permit  of  rocker  action  at  the  base,  as  in  the  Manhattan  and 
new  Budapest  bridges,  both  of  which  exhibit  the  highest  degree 
of  merit  yet  attained.  The  towers  for  the  proposed  North 
River  bridge  (Fig.  91)  were  to  be  octagonal,  625  feet  high, 
tapering  out  at  the  bottom  like  the  trunks  of  great  trees.  The 
designs  for  the  Budapest,  Manhattan  (Fig.  88)  and  North 
River  bridges  are  the  combined  work  of  engineers  and  archi- 
tects, and  their  beauty  contrasts  strongly  with  some  other  utili- 
tarian structures. 

Wooden  cable  supports  are  occasionally  used  for  light  or 
temporary  bridges,  and  when  well  enclosed  and  protected  from 
the  weather  may  last  for  half  a  century.  The  supporting  mem- 
bers are  heavy  timber,  which  are  enclosed  with  sheathing  on 
wooden  purlins.  They  may  be  battened  or  shingled  like  the 
old  Newburyport  towers,  and  painted  in  one  or  more  colors. 

CABLES 

Cables  are  now  made  either  of  high  tension  wire  or  eye 
bars,  the  first,  with  the  greatest  working  strength,  being  the 
lighter  but  requiring  the  longer  time  to  erect.  Steel  eye  bars 
are  more  quickly  erected,  but  with  a  lower  tensile  strength  are 
proportionately  heavier.  The  cables  of  early  suspension  bridges 
were  made  of  chain  links,  flat  iron  plates,  or  links  fastened 
together  with  bolts;  but  these  forms  are  no  longer  considered. 
No  aesthetic  treatment  can  be  given  to  the  cables  themselves, 
for  they  are  purely  structural  members,  but  much  can  be 
exhibited  in  the  method  of  loading  and  stiffening  them.  Loaded 
cables  in  the  end  spans,  as  in  the  Brooklyn  bridge,  with  end 
curves  corresponding  to  the  center  span,  are  more  beautiful 
than  straight  ones,  as  on  the  Williamsburg  bridge,  though  the 
latter  may  have  structural  preference.  When  the  end  cables 
are  unloaded,  the  platform  may  be  supported  on  metal  fram- 
ing and  piers,  as  at  Williamsburg,  or  on  a  series  of  stone  arches, 


98 


ARTISTIC  BRIDGE  DESIGN 


^- 


Fig.  91 


SUSPENSION  BRIDGES  99 

as  in  the  Roche  Bernard  bridge,  but  a  combination  of  arches 
and  loaded  end  cables,  as  in  the  Menai  bridge,  is  useless,  for 
either  one  without  the  other  would  sustain  the  platform.  When 
terminal  arches  are  used,  the  same  number  of  openings  should 
appear  at  each  end,  instead  of  the  unsymmetrical  arrangement 
of  the  Menai  bridge, 

METHODS  OF  STIFFENING  CABLES 

Flexible  suspension  bridges  are  stifFened  with  trussing,  either 
adjoining  the  cable  or  parallel  with  the  roadway.  The  former 
method  with  stiffened  cables  is  illustrated  by  the  two  Danube 
Canal  bridges  at  Vienna  (Fig.  87),  the  Jefferson  Avenue 
bridge  at  St.  Louis,  the  Seventh  Street  and  Point  bridges  at 
Pittsburg,  the  Tower  bridge  at  London  (Fig.  83),  and  Mr. 
Lindenthal's  designs  for  the  Manhattan  (Fig.  89),  Quebec  and 
North  River  (Fig.  90)  bridges,  but  horizontal  trusses  are 
used  on  the  East  River  suspension  bridges  as  they  were  finally 
built. 

Braced  cables  involve  the  use  of  eye  bars  with  a  lower  ten- 
sile strength  than  wire,  and  this  has  been  a  hindrance  to  a 
more  general  adoption  of  the  method.  That  the  result  is  satis- 
factory and  correct  cannot  be  doubted,  after  an  examination 
of  some  good  example  like  that  at  St.  Louis.  Crescent-shaped 
cable  bracing,  as  on  the  old  Point  bridge  at  Pittsburg  or  the 
Tower  bridge,  London  (Fig.  83),  is  not  as  beautiful  as  paral- 
lel chords,  and  wherever  possible,  preference  should  be  given  to 
the  latter  and  more  pleasing  form.  Comparative  estimates  for 
a  suspension  at  Cologne  with  a  720-foot  center  span  showed 
that  while  stiffened  eye  bars  had  a  greater  weight  than  wire, 
the  cost  of  the  designs  was  about  the  same,  and  the  eye  bars 
could  be  erected  in  much  less  time.  But  whether  the  stiffening 
trusses  adjoin  the  road  or  cables,  provision  for  expansion  must 
be  made  at  the  center,  for  large  suspension  bridges  like  those 
at  New  York  have  a  daily  center  rise  and  fall  of  several  feet, 
due  to  change  of  temperature.     For  this  reason  stiffening  trusses 


100  ARTISTIC  BRIDGE  DESIGN 

for  long  spans  are  frequently  half  the  length  between  the  towers, 
meeting  at  a  center  pin. 

RIGID  SUSPENSIONS 

Rigid  suspensions  with  stiff  bracing  between  the  cable  and  a 
horizontal  chord  at  the  floor  level  are  suitable  when  the  live 
load  is  small  enough  in  comparison  to  the  dead  load,  that  com- 
pression will  never  occur  in  the  vertical  suspenders.  The  type 
is  not  as  sincere  a?  other  forms,  for  it  is  easily  confused  with 
cantilevers,  and  is  therefore  not  as  desirable.  But  when  a 
stifFened  suspension  is  used,  care  should  be  taken  to  adopt  a 
correct  outline  and  avoid  the  disturbing  effect  illustrated  in 
the  Loschwitz  stiffened  suspension  bridge,  the  upper  curve  of 
which  is  a  hyperbola.  More  satisfactory  ones  are  those  at 
Frankfort  over  the  Main  and  Easton  over  the  Delaware. 

ANCHORAGES 

The  anchorage  is  purely  a  structural  part,  hidden  from 
view  below  the  ground,  and  aesthetic  treatment  is  possible  only 
on  such  erections  as  are  carried  above  the  roadway.  The  crea- 
tion of  massive  monuments  above  the  anchorage  is  appropriate 
to  show  where  they  are  buried,  and  to  add  extra  weight  where 
it  is  useful.  The  importance  of  the  bridge  need  be  the  only 
limit  to  the  amount  of  art  displayed.  Very  line  anchorages  are 
shown  on  the  Elizabeth  bridge  at  Budapest,  and  elaborate 
studies  were  made  for  one  of  the  large  bridges  at  New  York. 
Lateral  guy  ropes  or  anchor  cables  which  are  frequently  used 
on  light  bridges  detract  greatly  from  their  appearance,  as  they 
betray  weakness  in  the  structure  itself. 


CHAPTER  XI 
Masonry  Bridges 

Masonry  bridges  are  more  easily  made  attractive  than  any 
other  type,  for  the  arch  outhne  is  beautiful,  and  abundant 
precedent  is  available.  Engineers  and  architects  are  both 
accustomed  to  the  form  and  very  little  special  study  is  needed, 
but  architects  generally  prefer  masonry  bridges  to  steel,  as  the 
aesthetic  treatment  of  them  corresponds  more  nearly  with  the 
design  of  buildings.  The  bridges  which  are  most  difficult  to 
ornament  are  those  which  contain  large  steel  spans  between 
masonry  approaches.  The  two  kinds  of  material  and  types 
of  construction  must  be  treated  according  to  different  stand- 
ards of  art,  and  aesthetic  and  economic  principles  are  involved 
in  different  proportions.  Until  near  the  end  of  the  eighteenth 
century  bridges  were  made  exclusively  of  wood  and  stone.  The 
introduction  of  iron  and  steel  in  the  nineteenth  century,  and  the 
production  of  these  materials  at  low  cost,  caused  metal  con- 
struction to  supersede  masonry,  but  in  the  twentieth  century  the 
combination  of  the  two  materials  in  reinforced  concrete  and  the 
economic  production  of  cement  indicates  a  rapid  return  to  the 
more  permanent  and  substantial  masonry  type.  The  lasting 
quality  of  steel  bridges  was  at  first  greatly  over  rated,  and  those 
with  solid  floor  which  are  only  semi-permanent  often  cost  more 
than  masonry.  The  desired  degree  of  permanence  should 
therefore  receive  full  consideration  before  selecting  between 
steel  and  masonry.  The  beautiful  bridges  at  the  great  exposi- 
tions of  the  last  half  century  were  splendid  illustrations  of 
designs  which  might  be  reproduced. 

ARRANGEMENT  AND  LENGTH  OF  SPANS 

More  than  ninety  per  cent  of  all  masonry  bridges  have 
spans  less  than  1 50  feet,  and  the  greatest  one  ever  attempted — 

101 


102  ARTISTIC  BRIDGE  DESIGN 

recently  completed  at  Rome — has  a  length  of  only  328 
feet.  Masonry  spans  are  therefore  always  short  in  comparison 
with  steel,  and  the  long  ones  of  the  future  will  doubtless  con- 
tinue to  be  of  metal. 

The  length  of  span  is  usually  determined  by  local  condi- 
tions, short  ones  being  best  suited  for  shallow  water  with 
little  current,  while  longer  ones  are  more  appropriate  over 
deep  and  rapid  rivers  or  busy  navigable  channels.  Bridges  of 
many  spans  appear  best  when  the  center  one  is  longer  than 
the  others,  and  adjoining  ones  decrease  in  length  towards  the 
ends.  Trajan's  six-span  bridge  at  Alcantara  (A.  D.  105) 
was  of  this  form,  for  the  two  center  openings  were  the  longest, 
and  at  each  side  were  smaller  ones.  The  arches  were  semi- 
circular, with  crowns  at  the  same  elevation  and  springs  rising 
towards  the  abutments. 

Unsymmetrical  curves  are  suitable  and  permissible  for 
approach  spans  over  sloping  hillsides,  as  in  three-span  bridges 
over  railroad  cuttings  where  the  abutment  springs,  to  be  above 
the  ground,  must  usually  be  higher  than  those  over  the  two  cen- 
tral piers.  But  when  the  shore  spans  are  shorter  than  the 
adjoining  ones,  and  springs  are  retained  at  a  uniform  level, 
the  crowns  may  all  be  kept  at  the  same  level  and  a  greater 
angle  of  curvature  used  in  the  side  spans.  Or,  if  the  same 
angle  is  retained  in  all,  the  crown  of  the  side  spans  will  be 
lower  than  the  others  and  the  roadway  over  them  may  be 
graded,  as  in  Ponte  Rotto  (Fig.  5)*  and  other  old  Roman 
bridges.  Too  much  roadway  grade  is,  however,  neither  at- 
tractive nor  convenient,  and  some  which  were  steeply  graded, 
like  Pont-y-Prydd  and  the  Claix  bridge  in  France,  have  now" 
more  convenient  bridges  built  beside  them,  with  level  roadway. 

Much  economy  results  from  using  separated  twin  arch 
rings,  as  at  Luxemburg,  and  Walnut  Lane  (Fig.  196),  Phila- 
delphia, which  are  possible  in  stone,  and  still  greater  economy 
in  reinforced  concrete  by  eliminating  all  useless  material  and 

*  From  Concrete  Bridges  and  Culverts.    By  H.   G.   Tyrrell. 


MASONRY  BRIDGES 


103 


retaining  only  structural  members,  as  in  a  steel  arch.  When 
carefully  treated  with  graceful  curves,  the  ribbed  arch  with  its 
lighter  appearance  may  be  made  more  artistic  than  the  more 
solid  ones  with  spandrel  filling.  Excellent  examples  are  those 
at  Sandy  Hill,  N.  Y.,  over  the  Hudson,  which  is  faced 
with  concrete  blocks,  and  a  proposed  design  (Fig.  92)  for  the 


Fig.  92 


Grand  Avenue  viaduct  at  Milwaukee.  A  less  fortunate  con- 
crete cantilever  arch  crosses  the  Vermilion  river  at  Wakeman, 
O.,  which,  though  original  constructively,  is  lacking  in  aesthetic 
treatment. 


THE  DECK 

Masonry  bridges,  like  all  others,  should  have  their  decks 
symmetrically  and  carefully  arranged,  with  enough  space  for 
traffic.  Provision  must  be  made  for  pipes  and  wires  in 
covered  and  accessible  chambers  beneath  the  roadway,  and 
the  mistake  in  the  London  bridge  avoided  where  these  utilities 
are  placed  on  the  main  cornice  outside  the  railing,  greatly 
marring  its  elegance. 


104 


ARTISTIC  BRIDGE  DESIGN 


Change  of  roadway  grade  should  follow  a  uniform  ver- 
tical curve  rather  than  straight  planes,  and  in  the  absence  of  a 
cornice  the  roadway  should  be  indicated  on  the  face  by  a  belt 
course. 

SPANDRELS 

Spandrels  are  of  two  kinds,  solid  and  open.  Solid  span- 
drels, with  face  walls  either  to  retain  earth  filling  or  as  a  cur- 
tain, may  be  treated  in  several  ways  which  are  difFerent  for 
stone  and  concrete.  Monolithic  concrete  should  be  moulded 
in  continuous  curves  and  cornices,  as  on  the  Grosvenor  bridge 
(Fig.  93),  England,  while  stone  or  other  block  structures 
should  have  the  lines  or  joints  accentuated.     The  Grosvenor 


Fig.  93 


and  Schenley  Park  bridges  have  sunken  triangular  spandrel 
panels,  which  are  more  suitable  for  small  bridges  than  large 
ones.  The  great  295-foot  arch  at  Plauen  (Fig.  18)  has  cir- 
cular recesses  in  the  spandrel  walls  similar  to  Pont-y-Prydd, 
the  effect  of  which  is  good,  and  others  like  the  London  and 
Waterloo  bridges  have  no  other  marking  than  the  horizontal 
chisel  drafts  on  the  stone  courses.  An  elegant  effect  is  shown 
on  a  small  bridge  in  Golden  Gate  Park,  San  Francisco,  and 
still  better  treatment  is  displayed  in  the  carvings  of  the  spandrel 
panels  on  Ponte  Rotto  and  the  Rialto  (Fig.  187),  the  last 
containing  figures  of  angels. 

Large  plain  surfaces  should  be  broken  up  with  belt  courses, 
pilasters  or  other  markings,  for  without  them  small  irregulari- 
ties in  plumb  and  level  lines  are  more  evident.     But  panels  on 


MASONRY  BRIDGES  105 

large  bridges  must  not  be  too  small  or  fine,  for  they  then  pro- 
duce a  diminutive  effect.  False  arches  on  the  face  wall  with 
pilasters  between  them  relieve  otherwise  flat  surfaces,  but  such 
arches  lack  sincerity.  Hollow  spandrels  should  show  hollow 
on  the  face  and  should  not  be  concealed  by  curtain  walls. 
This  type  offers  much  opportunity  for  artistic  treatment,  and 
may  be  made  either  with  arcades  or  colonnades.  Transverse 
arcades  are  suitable  only  for  comparatively  narrow  bridges, 
for  a  slightly  oblique  view  on  wider  ones  obstructs  the  sight 
through  the  arcade  and  injures  the  contrast    (Fig.  94).     A 


Fig.  94 

really  elegant  effect  m  open  spandrels  is  secured  with  a  cen- 
tral arch  above  the  pier  and  an  adjoining  one  in  each  span,  as 
in  the  Tarn  River  bridge  at  Albi,*  the  idea  being  borrowed 
from  the  Romans.  The  spans  of  transverse  spandrel  arches 
supporting  the  roadway  should  increase  towards  the  abutments 
with  their  greater  height,  as  in  the  Salcano  bridge  in  Austria. 
When  these  minor  arches  are  of  uniform  width,  the  arrange- 
ment usually  appears  inconsistent. 

An  excellent  and  very  economical  design  for  a  concrete  arch 
of  1 50-foot  span,  is  illustrated  in  Fig.  95.     In  some  respects 

*  American  Architect,  Oct.  19,  1901. 


106 


ARTISTIC  BRIDGE  DESIGN 


the  curtain  walls  cause  the  design  to  be  insincere;  the  walls, 
however,  serve  the  useful  purpose  of  enclosing  the  metal  span- 
drel framing  from  the  weather  and  at  the  same  time  allow  the 
interior  hollow  portion  to  remain  in  a  rougher  or  less  finished 
condition,  thus  saving  expense.     The  thickness  of  arch  ring  is 


Half  Elevation 
of  Completed  Structune. 


Fig.  95 


shown  on  the  face,  and  at  each  side  of  the  opening  are  heavy 
pilasters.  The  foundations  also  are  worthy  of  note.  The 
Topeka  bridge  (Fig.  96),  by  the  same  engineer,  is  quite  dif- 
ferent from  the  last,  for  it  has  flatter  arches  with  solid  earth 
filling  in  the  spandrels. 


Fig.  96 


ARCH  RINGS 


Arch  rings  should  be  truly  represented  on  the  face  with 
thickness  increasing  towards  the  springs,  and  when  surmounted 
by  solid  spandrels  the  rings  should  be  indicated  and  empha- 
sized by  a  projecting  stone  course.  Moulded  outlines  only 
are  suitable  in  concrete,  and  in  this  material  keystones  or  other 


MASONRY  BRIDGES  107 

imitative  features  are  inappropriate  and  untrue.  The  prac- 
tice which  is  common  in  buildings,  of  making  arch  rings  deeper 
at  the  center  than  at  the  springs,  should  be  avoided  in  bridges, 
as  it  is  an  untruthful  representation  and  gives  the  effect  of  over- 
balance. It  frequently  results  from  making  voussoir  joints 
match  the  horizontal  spandrel  courses,  the  upper  side  of  the 
arch  stones  being  cut  with  vertical  and  horizontal  faces,  that 
the  horizontal  thrust  of  the  backing  may  be  effective. 

SHAPE  AND  PROPORTION 

The  appearance  of  masonry  bridges  depends  chiefly  on 
the  arch  curve,  and  a  form  should  be  selected  which  is  the 
most  pleasing  consistent  with  construction.  The  common 
forms  are  (1)  the  semicircle,  (2)  the  ellipse,  and  (3)  the 
circular  segment.  The  first  is  preferable  for  long  series  of 
arches  or  high  viaducts,  and  it  was  universally  used  on  Roman 
aqueducts  and  on  many  later  ones,  such  as  Roquefavour  and 
High  Bridge  at  New  York  (Fig.  190).  The  semicircle  and 
ellipse  are  always  satisfying,  the  ellipse  being  merely  an  oblique 
view  of  the  circle.  But  neither  of  these  forms  correctly  shows 
the  line  of  pressure  further  than  the  point  of  rupture,  for  any 
portion  of  the  arch  below  that  point  is  really  part  of  the  pier 
or  abutment.  For  comparatively  flat  arches,  a  curve  of  the  same 
rise  half  way  between  a  segment  and  an  ellipse  corre- 
sponds closely  with  the  line  of  pressure,  but  departure  from 
exact  curves  produces  optical  discord.  The  segment  is  the 
correct  constructive  form  exhibiting  greatest  strength,  but  the 
semicircle  and  ellipse  are  acceptable  for  their  fine  appearance. 
Ellipses  seem  to  be  weak  when  they  have  too  small  a  rise,  the 
flat  central  part  contrasting  with  the  greater  curvature  at  the 
springs.  Lines  are  appropriate  on  the  face  of  semicircular  and 
elliptical  arches,  which  represent  the  true  line  of  thrust,  ma- 
terial below  this  line  near  the  springs  being  ineffective  except- 
ing for  appearance.  Segmental  and  elliptical  arches  appear 
to  best  advantage  on  low  bridges,  for  the  form  originated  from 


108 


ARTISTIC  BRIDGE  DESIGN 


I 


...ii 


insufficient  space  for  a  greater  rise.  The  conoidal  form,  orig- 
inated by  Perronet,  with  segmental  face  tapering  to  an  ellipse 
at  the  center  of  the  soffit,  was  used  on  the  Neuilly  (Fig.  113) 
and  Dora  Riparia  bridges  near  Turin,  and  was  quite  econom- 
ical of  material.  The  form  offered 
less  obstruction  to  the  passage  of  water 
and  drift  than  a  complete  elliptical 
arch. 

Ellipses  should  be  exact  curves  or 
drawn  from  at  least  nine  to  eleven 
centers.  The  usual  three  or  five- 
center  approximations  to  the  true  curve 
betray  their  inaccuracy.  The  amount 
of  rise  is  essential  and  should  be 
enough  to  exhibit  strength.  Ellipses 
which  are  too  flat,  appear  weak  and 
insecure,  a  rise  of  one-fourth  the  span 
giving  the  most  pleasing  proportion. 
A  good  aesthetic  effect  is  produced  by 
using  an  ellipse  for  the  center  span, 
with  smaller  semi-circular  arches  at 
the  side,  as  in  the  railroad  bridge 
(Fig.  97)  designed  by  the  writer  for 
crossing  an  irrigation  canal  in  Idaho. 
Springs  appear  best  when  at  the 
same  level.  They  should  be  marked 
by  copings  and  should  always  be  above 
high  water,  rather  than  occasionally 
submerged,  as  in  old  bridge  at  Avig- 
non. In  this  respect  the  Roman 
bridges  were  lacking,  for  they  fre- 
quently had  springs  at  different  levels, 
as  in  Trajan's  bridge  at  Alcantara. 
When  the  space  beneath  the  bridge  is  so  small  that  the  base  of 
semi-circular  arches  would  be  under  water,  the  choice  then  must 
be  between  shorter  spans  and  flatter  curves.   Over  foot  paths  or 


T 


.^^^^1 


MASONRY  BRIDGES  109 

side  walks,  there  should  be  at  least  six  feet  headroom  at  the 
springs,  and  if  this  is  impossible  a  railing  or  partition  wall  should 
divert  travel  away  from  the  lower  part,  rather  than  leave  the 
path  exposed  and  pedestrians  liable  to  injury,  as  on  the  Long- 
wood  bridge  (Fig.  166). 

Arches  supporting  sidewalks  are  sometimes  made  flatter 
than  those  under  the  roadway,  and  piers  somewhat  thinner,  as 
on  Telford's  bridges  at  Cartland  Craigs,  and  Edinburgh.  The 
method  may  also  be  used  to  advantage  for  widening  old 
bridges,  for  the  new  flat  arch  is  not  an  extension  of  the  old  one, 
and  the  addition  is  not  so  evident. 

PIERS 

Piers  are  of  two  kinds,  ( 1 )  those  which  support  high 
level  bridges  and  (2)  low  piers  such  as  those  for  ordinary  flat 
bridges.  All  river  piers  must  have  cut  waters,  and  these  are 
most  prominent  on  low  structures,  frequently  being  the  most 
notable  portion.  Piers  are  either  simple  supporting,  or  abut- 
ment piers.  The  Romans  generally  used  all  of  the  latter  type, 
and  to  their  presence  is  due  the  partial  preservation  of  many 
old  Roman  bridges  such  as  Ponte  Rotto  (Fig.  100)  and 
Avignon.  Ponte  Rotto,  which  was  first  constructed  of  stone 
during  the  years  B.  C.  1  78-142,  continued  in  use  until  A.  D. 
1 890,  when  it  was  replaced  by  a  skew  bridge  with  steel  trusses 
on  piers  parallel  to  the  current.  In  modern  practice  low  and 
long  spans  require  heavy  piers,  while  high  and  short  spans  need 
lighter  ones.  When  a  pier  occupies  a  central  position  in  a 
bridge  of  more  than  one  span,  it  should  be  large,  or  conspicuous 
enough  to  be  a  predominating  feature,  and  the  efFect  is  improved 
if  erections  are  continued  above  the  deck.  When  drain  pipes 
from  the  roadway  are  conducted  down  their  side,  they  should 
be  built  into  the  masonry  rather  than  exposed  on  the  face  or 
placed  in  grooves. 

The  chief  parts  of  piers  are  the  base,  the  body  and  the 
coping.     Tall  ones  should  have  a  batter  on  all  sides  and  the 


no 


ARTISTIC  BRIDGE  DESIGN 


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Fig.  98 


Fig.  99 


Fig.  100 


Fig.  101 


MASONRY  BRIDGES 


111 


Fig.   102 


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Fig.    104 


Fis-  lOJ 


Fig.   106 


112  ARTISTIC  BRIDGE  DESIGN 

body  may  be  varied  by  one  or  more  belt  courses,  though 
height  is  emphasized  by  an  unbro-ken  shaft.  Sides  slightly 
curved,  as  on  the  approach  piers  to  the  Forth  bridge,  appear 
very  graceful  and  give  the  desired  extra  width  at  base. 

Footing  courses,  cut  waters  and  nosing  are  the  principal 
parts  below  the  springs.  Pointed  ends  are  more  effective  than 
round  ones,  and  they  should  have  a  hard  stone  or  iron  nosing, 
but  round  ends  are  more  pleasing.  Curved  outlines  for  piers 
as  on  the  Maumee  river  bridge  (Fig.  215)  at  Waterville,  are 
appropriate  in  concrete,  and  show  a  correct  use  of  moulded 
material,  in  contrast  to  stone. 

SPACE  ABOVE  PIERS 

Piers  which  seem  to  terminate  at  or  about  the  springs,  usu- 
ally have  a  stunted  appearance,  and  most  of  the  finest  bridges 
have  decorative  features  up  to  or  above  the  balustrade.  This 
position  is  in  fact  the  principal  opportunity  for  displaying  orna- 
ment. The  Romans  frequently  used  small  arch  openings 
through  the  piers  above  the  springs  as  in  Fabricius  (Fig.  98), 
and  Rotto  (Fig.  100),  which  gave  extra  water  way  in  flood 
seasons.  On  both  these  bridges  at  each  side  of  the  minor 
arches  were  semi-columns.  The  bridge  at  Rimini  was  orna- 
mented with  panels  (Fig.  99)  at  each  side  of  which  were  col- 
umns supporting  a  pediment.  Bridges  of  the  middle  ages  like 
those  at  Dresden  and  Limoges,  had  cut  waters  continued  up  to 
the  deck,  the  upper  part  forming  retreats  in  the  balustrade. 
The  heavy  cut  waters  of  the  Dresden  bridge  are  its  principal 
characteristic.  As  the  purpose  of  columns  is  to  sustain  weight, 
when  they  are  used  above  the  cut  waters  they  should  at  least 
appear  to  support  a  load  such  as  an  extension  of  the  sidewalk, 
a  statue,  or  lamp  cluster.  Some  of  the  finest  bridges  in  Berlin 
(Figs.  107,  108)  and  London  are  adorned  on  the  spandrels 
above  the  piers  with  statuary,  and  the  Chatsworth  bridge  (Fig. 
194)  on  a  private  estate  in  England,  shows  similar  treatment. 
The  new  Cambridge  bridge  over  the  Charles  river  at  Boston 


MASONRY  BRIDGES  113 

exhibits  the  prow  of  a  boat  emerging  from  the  pier,  and  a  sim- 
ilar feature  may  be  found  on  the  old  Margaret  bridge  at  Buda- 
pest. Double  pillars  as  on  Rennie's  Waterloo  and  Kelso 
bridges,  are  striking  ornaments,  but  appear  less  substantial  than 
the  plain  pilasters  of  London  bridge.  Single  large  semi- 
columns  above  the  triangular  cutwaters  of  Pont  Neuf  at  Paris, 
support  sidewalk  retreats,  the  position  of  which  are  emphasized 
by  double  lamp  standards  at  each  side. 

Niches  in  piers  are  features  more  suited  to  small  bridges 
than  to  large  ones.  Most  of  the  features  on  the  spandrel  face 
above  the  piers  which  are  described  above,  interfere  with  and 
seem  to  cross  the  ends  of  the  arch  rings,  though  this  is  avoided 
in  the  design  of  Fig.  1 07. 

ABUTMENTS 

The  design  of  abutments  should  harmonize  with  the  piers, 
and  they  should  not  only  be  sufficient,  but  should  appear  heavy 
enough  to  resist  the  thrust  upon  them.  The  apparent  strength 
of  abutments  is  often  injured  by  the  presence  of  smaller  arches 
which  penetrate  them  just  where  weight  is  most  needed.  Abut- 
ment faces  should  have  a  batter,  for  without  it  they  seem  to  be 
top  heavy  and  unstable.  The  base  or  lower  part  should  be 
plain,  and  the  amount  of  detail  ornament  increased  towards 
the  parapet.  Curved  wing  walls  add  greatly  to  the  aesthetic 
effect,  and  even  when  plain  girders  are  imperative  as  at  the 
entrance  to  Forest  Park,  St.  Louis,  carefully  designed  abut- 
ments may  in  themselves  add  enough  beauty  to  the  bridge. 
Cantilever  wing  walls  as  on  the  Topeka  bridge,  are  possible 
in  reinforced  concrete,  and  are  much  lighter  than  solid  ones 
which  must  depend  on  their  weight  for  stability.  On  the 
writer's  design  for  an  ornamental  park  bridge  (Fig.  159),  the 
arches  shown  on  the  abutment  faces  may  be  merely  wall  decora- 
tion, in  which  case  the  bridge  floor  may  be  carried  either  on 
solid  earth  filling  or  on  interior  framing.  If,  however,  the 
arch  ways  are  required  open  for  foot  walks  or  for  other  pur- 


114 


ARTISTIC  BRIDGE  DESIGN 


Fig.   107 


Fig.   108 


Fig.   100 


MASONRY  BRIDGES 


115 


Fig.   110 


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Fig.   112 


Fig.   113 


116 


ARTISTIC  BRIDGE  DESIGN 


Fig.   114 


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Fig.   115 


MASONRY  BRIDGES  117 

pose,  the  filling  will  then  be  placed  above  the  arches.  The 
latter  method,  though  costing  more,  will  give  a  better  effect 
than  the  arrangement  with  false  arches,  for  the  end  and  center 
openings  will  have  the  additional  interest  of  contrast. 

PARAPETS  AND  BALUSTRADE 

No  part  of  a  bridge  is  more  often  seen  than  its  parapet, 
and  in  no  place  is  fine  ornament  more  appropriate.  The  degree 
of  art  displayed  should  correspond  with  the  importance  of  the 
structure  and  the  amount  of  travel  which  passes  over  it.  Rail- 
road bridges  with  little  or  no  pedestrian  travel  may  need  no 
balustrade,  and  even  when  sidewalks  are  present,  embellish- 
ment cannot  be  so  well  enjoyed  as  on  street  bridges,  and  the 
latter  class  should  therefore  exhibit  the  finest  effects. 

Balustrades  are  either  solid  or  open.  Solid  ones  over  thin 
arch  rings  appear  to  add  greater  depth  and  strength  to  light 
designs  and  for  this  reason  they  are  often  preferred.  But 
parapets  should  not  be  so  heavy  as  to  make  it  seem  that  the  only 
duty  of  the  arch  was  to  support  them.  Excellent  examples  of 
solid  railings  are  on  Ponte  Rotto  at  Rome,  and  Pont  Neuf  at 
Paris.  On  the  contrary  very  heavy  arches  should  have  a 
light  open  railing  like  the  metal  ones  on  High  Bridge  (Fig. 
190)  at  New  York.  Municipal  bridges  are  generally  heavy 
enough  to  make  an  open  and  more  ornate  balustrade  prefer- 
able. Their  height  varies  from  three  to  five  feet,  the  usual 
being  three  and  one-half  feet. 

The  parts  of  balustrades  are  the  cap  or  coping,  the  dado 
or  central  part,  and  the  plinth  or  base,  the  latter  part  some- 
times including  a  cornice.  A  smooth  coping  is  most  appro- 
priate, forming  a  convenient  hand  rest  and  the  neatest  finish, 
a  fine  effect  being  shown  on  the  Forest  Hills  Cemetery  bridge, 
which  has  white  stone  over  a  grey  rustic  dado.  In  other  cases 
the  coping  is  made  of  the  same  material  as  the  cornice  and 
arch  rings,  with  intervening  parts  of  a  different  nature  and 
color.  The  embrasures  of  battlemented  copings  as  on  the 
Tongueland    (Fig.     104)     and    Cahors    bridges,    should    be 


ARTISTIC  BRIDGE  DESIGN 


Fig.   116 


Fig.   117 


Fig.   118 


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Fig.   120 


MASONRY  BRIDGES 


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120 


ARTISTIC  BRIDGE  DESIGN 


Fig.   126 


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Fig.   127 


Fig.  128 


Fig.   129 


MASONRY  BRIDGES  121 

guarded  with  metal  rods  to  avoid  openings  of  too  great  a  size. 
A  rustic  coping  may  be  made  by  placing  thin  stones  on  edge 
embedded  in  the  wall  beneath  them,  as  on  the  Cresheim  Creek 
bridge  at  Philadelphia,  but  the  design  is  suitable  only  in  rough 
surroundings,  or  where  the  balustrade  is  intended  to  be  repel- 
lent. 

The  dado  or  central  part  is  usually  the  most  elaborate,  the 
amount  of  ornament  being  limited  only  by  the  prominence  of 
the  structure.  The  base  course  or  plinth  should  in  the  absence 
of  a  cornice  indicate  the  grade  of  the  road  or  sidewalk  by  a 
projecting  string  course.  A  decided  camber  is  appropriate  on 
low  bridges,  showing  the  useful  purpose  of  increased  clearance 
underneath,  but  high  bridges  may  have  a  flatter  grade.  Foot 
bridges  over  railway  cuttings  or  canals,  which  have  excessive 
grade  or  stepped  approach,  may  have  level  courses  in  the  para- 
pet capped  with  an  anchored  coping,  or  the  coping  may  be 
stepped  at  intervals  corresponding  with  the  rising  floor,  as  on 
the  bridges  at  Torcello,  Italy,  and  Belle  Isle  Park,  Detroit. 
The  cambered  coping  of  the  Boylston  bridge  is  one  of  its  most 
interesting  outlines.  Intermediate  pedestals  are  not  desirable 
in  balustrades  with  excessive  camber,  for  their  plumb  and  hori- 
zontal lines  are  out  of  harmony  with  the  sloping  lines  of  the 
balustrade  adjoining  them.  But  on  flatter  bridges  they  are 
most  appropriate,  and  offer  much  diversity  of  design  and  treat- 
ment. They  should  be  placed  over  the  piers  and  at  the  ends, 
and  a  few  intermediate  smaller  ones  in  the  railing  add  variety. 
End  pedestals  should  be  the  largest  and  most  prominent,  and 
in  some  bridges  they  have  been  made  large  enough  to  represent 
toll  houses.  Two  intermediate  ones,  dividing  the  railing  over 
each  arch  into  three  panels,  produce  a  good  effect  and  were 
used  on  the  beautiful  Wellesley  bridge  at  Limerick;  but  they 
may  be  more  numerous  as  on  the  Rittenhouse  Lane  bridge  at 
Philadelphia.  Turned  stone  balls  are  good  balustrade  orna- 
ments, as  on  Kings  Bridge,  Nuremburg,  or  on  one  in  Golden 
Gate  Park,  San  Francisco,  Balustrades  may  be  made  of  sev- 
eral materials  and  in  great  variety.     A  few  designs  are  illus- 


122 


ARTISTIC  BRIDGE  DESIGN 


Fig.   131 


Fig.   132 


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Fig.   133 


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MASONRY  BRIDGES 


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ARTISTIC  BRIDGE  DESIGN 


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MASONRY  BRIDGES  125 

trated,  in  rustic  wood,  cut  stone,  brick,  artificial  stone,  terra 
cotta,  cast  iron  and  wrought  metal,  though  some  designs  which 
have  been  executed  in  one  material  are  equally  appropriate  in 
others.  Fig.  1  1 6  and  Fig.  1  1  7  are  suitable  for  foot  bridges  in 
wooded  dells  of  private  estates  or  parks,  while  Figs.  118,  119, 
120,  121  and  144  could  be  made  in  cast  iron  or  terra  cotta. 
Figs.  122,  124,  125  and  139  could  be  nicely  executed  in 
brick,  and  Fig.  132,  which  is  the  balustrade  on  the  Connecti- 
cut avenue  bridge  at  Washington,  has  beauty  of  contrast,  with 
light  iron  railing  between  heavy  masonry  supports.  Fig.  1 33 
is  the  balustrade  on  the  beautiful  Memorial  bridge  at  Hartford, 
designed  by  George  Kellar  and  more  fully  shown  in  Fig.  14. 
Turned  balusters  of  stone  or  metal.  Figs.  135,  138,  145,  146 
and  147,  are  more  used  on  the  fine  bridges  of  Europe  than 
any  other  form.  They  frequently  correspond  with  parts  of  ad- 
joining buildings,  and  the  detail  is  never  tiresome.  Large 
dado  openings  as  on  the  Garfield  Park  bridge  (Fig.  129) 
should  be  guarded  with  embedded  metal  bars.  Figs.  148  to 
1  58  are  suitable  in  bronze  or  iron. 

MATERIAL,  COLOR,  AND  SURFACE  FINISH 

Harmony  of  color  affects  the  senses  in  a  similar  way  to 
harmony  of  sounds.  Structural  parts  like  arch  rings  and  piers 
may  be  appropriately  emphasized  in  material  of  a  different 
color  to  the  rest,  as  in  the  Rock  River  bridge  at  Watertown, 
Wis.  A  fine  mottled  effect  with  beauty  of  contrast,  is  obtained 
with  a  concrete  surface  finish  of  crushed  black  stone,  showing 
the  grey  concrete  body  between  the  facing  pebbles. 

Below  the  springs,  piers  may  be  made  of  r-ougher  or  darker 
material  than  the  part  above  that  level,  as  on  High  Bridge  at 
New  York  (Fig.  190),  or  the  Chatsworth  bridge  (Fig.  194), 
which  has  rough  stone  piers  and  smooth  spandrels.  Concrete 
must  not  be  made  to  imitate  stone,  for  the  result  is  not  only 
false  but  disappointing.  Glazed  brick  in  different  shades  con- 
trasts well  with  stone  and  is  used  with  fine  e-ffect  in  the  spandrels 
of  the  Sixth  street  bridge  at  Des  Moines,  Iowa,  and  in  the  soffits 


126 


ARTISTIC  BRIDGE  DESIGN 


Fig.   148 


Fig.  149 


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Fig.  151 


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MASONRY  BRIDGES 


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Fig.  153 


Fig.   154 


Fig.   155 


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ARTISTIC  BRIDGE  DESIGN 


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MASONRY  BRIDGES  129 

of  Stony  Brook  bridge  (Fig.  168)  in  the  Boston  Fenways, 
while  greater  elegance  is  shown  by  the  light  colored  frieze 
course  on  the  portal  tower  of  the  Hartford  Memorial  bridge. 
Excellent  color  combination  in  grey  and  reddish  concrete,  is 
exhibited  in  Piney  Creek  bridge  at  Washington.  Rough  stone 
face  is  the  most  appropriate  for  heavy  bridges  in  rural  dis- 
tricts as  on  the  railroad  bridge  (Fig.  192)  over  the  entrance 
to  the  wooded  Wissahickon  valley,  and  a  more  rustic  appear- 
ance is  displayed  in  the  Waldi-Tobel  bridge  in  Austria.  A 
fine  surface  finish  is  secured  with  moulded  concrete  facing 
blocks,  as  in  the  Connecticut  avenue  and  Sandy  Hill  bridges 
and  on  the  ornamental  park  bridge  (Fig.  159)  designed  by 
the  waiter  ten  years  ago.  In  the  last  case  the  arch  ring  and 
all  corners  and  moulding  are  of  concrete  blocks,  while  the 
balustrade  is  of  artificial  stone.  The  two  piers  at  each  side 
project  out  past  the  face  of  the  arch  and  are  ornamented  with 
shields,  and  above  the  piers  the  balustrade  is  offset  two  feet, 
forming  retreats  from  the  sidewalks  in  which  seats  are  pro- 
vided under  the  electric  lamps.  Unsightly  and  irregular  marks 
on  concrete  surfaces  are  avoided  by  placing  triangular  strips 
over  the  plank  joints,  which  produce  horizontal  lines  on  the 
finished  masonry.  The  expedient  is  not  an  imitation  of  stone 
courses,  but  is  used  rather  to  emphasize  the  form  joints  since 
they  cannot  be  avoided.  On  flat  surfaces  iregularities  are  too 
evident,  and  this  method  of  lining  the  face  produces  an  effect 
similar  to  that  on  the  spandrels  of  London  bridge.  Roman 
bridges  with  concrete  bodies  were  usually  faced  with  traver- 
tine, but  as  moulded  concrete  blocks  are  now  easily  obtainable, 
they  are  usually  more  appropriate. 


Fig.   160 


FIGURE  160.      Bridge  in  Japanese  Tea  Garden,   San  Francisco 

These  little  rustic  bridges  are  typical  of  many  found 
in  Japanese  gardens.  They  are  called  "Drum"  or 
"Bow"  bridges  and  are  curved  upward,  giving  space  for  the 
passage  of  boats.  The  drum  is  provided  with  steps  for 
climbing  the  ascent,  and  it  has  a  railing  at  each  side.  They 
are  quite  ornamental  and  appropriate  for  Japanese  gardens, 
of  which  there  are  many  in  cities  outside  of  Japan. 


131 


Fiu'.    !'■'! 


FIGURE   161.      Rustic  Bridge   in  Minneapolis;  Minn. 

Located  among  the  trees  and  across  the  path,  in  a  small 
ravine,  is  a  very  appropriate  little  foot  bridge.  It  is  extremely 
well  suited  to  the  surroundings,  and  was  built  in  1893.  The 
design  is  ordinary  but  satisfying,  because  of  its  fitness. 


133 


FIGURE    162.      Log  Bridge   at  Washington,  D.   C. 

A  very  interesting  and  unusual  example  of  rustic  construc- 
tion was  built  a  few  years  ago  in  the  National  Zoological 
Park  at  Washington.  It  is  a  log  arch  of  75  ft.  span  and  30 
ft.  wide.  The  total  cost,  including  macadam  roadway  and 
foot  walks,  was  about  $3,000. 


iHf) 


FIGURE  163.     Bridge  at  Belle  Isle  Park,  Detroit,  Mich. 

Belle  Isle  Park  at  Detroit  is  approached  from  the  city  by 
crossing  several  bridge  spans  having  through  metal  trusses, 
which  are  suitable  only  for  some  outlying  district  where  they 
would  be  seldom  seen,  but  within  the  park  are  several  very 
attractive  bridges,  one  of  which  is  herewith  illustrated.  The 
long,  uncouth  and  gaunt  steel  bridge  over  one  channel  of  the 
river,  from  the  city  to  the  park,  stands  out  in  strikmg  contrast 
to  the  beautiful  bridges  among  the  foliage,  and  shows  the 
difference  between  factory-made  products  and  those  designed 
by  an  engineer  artist. 


137 


FIGURE  164.      Arch  Bridge  in  Garfield  Park,  Chicago 

In  this  bridge  the  semi-cokimns  at  the  terminus  of  the 
arch  and  the  end  newels,  together  with  the  ornamental  cop- 
ing and  heavy  open  balustrade,  unite  to  produce  a  very 
pleasing  effect.  At  either  side  are  medallions  bearing  the 
park  initials  in  monogram,  and  on  the  spandrels  is  the  date  of 
construction,  1 893. 


K-iJ-i 


FIGURE   l'B5.      Brick  Arch  Bridge  over  North  Ravine,  Lake  Park, 

MiWaukee 

This  arch  was  built  in  1893,  and  has  a  clear  span  of 
35  ft.  The  arch  stones  and  trimmings,  as  well  as  the  rail- 
ings, are  of  terra-cotta,  the  spandrel  faces  and  wing  walls 
of  brown  face  brick,  and  the  body  of  the  arch  of  five  rings 
of  hard  burned  sewer  brick  laid  in  cement.  It  has  a 
26-foot  roadway  and  two  walks  each  6  ft.  wide  and  its 
total  length  is  1 00  ft.  It  is  the  design  of  Oscar  Sanne,  and 
was  completed  at  a  cost  of  $10,500. 


141 


FIGURE    166.      Longwood   Bridge,    Boston,    Mass. 

The  view  shows  Longwood  bridge,  in  the  Boston  Park 
system,  which  is  a  modification  from  the  plan  prepared  by 
Shepley,  Rutan  and  Coohdge,  architects.  The  estimate  on 
this  bridge  in  rock-faced  ashlar  with  soffits  of  brick,  was 
$153,000.  The  original  sketch  showed  steps  at  both  ends, 
leading  from  the  bridge  to  the  walks  underneath,  and  also 
showed  more  decorative  features,  such  as  blind  abutment 
arches,  medallions  at  the  spandrels,  and  heavy  pilasters  at 
the  ends  of  the  arch,  carrying  sidewalk  lookouts  or  retreats. 
The  grade  of  the  street  is  so  low  that  there  appears  to  be 
insufficient  head  room  for  the  paths  beneath,  an  objection 
which  might  have  been  overcome  by  using  three  spans  instead 
of  one.  The  balustrade  is  solid  without  openings,  and  has 
a  coping  of  different  material. 


143 


FIGURE   167.      Forest  Hills  Entrance  to  Franklin  Park,  Boston 

A  beautiful  structure  in  Franklin  Park,  Boston,  was  built 
to  carry  the  parkway  over  the  traffic  road  from  Forest  Hill 
street  to  Forest  Hills  Cemetery.  This  bridge  is  125  ft.  long, 
and  the  main  span  is  a  segmental  arch  of  45  ft.  A  stairway 
connects  the  walk  over  the  bridge  with  a  footway  along  the 
traffic  road  beneath,  and  the  slopes  of  the  bank  are  supported 
by  retaining  walls.  Crossing  the  parkway  over  the  bridge  is 
a  gateway,  the  masonry  piers  for  which  have  been  built.  This 
gateway  has  three  openings,  one  each  for  the  drive,  the  walk 
and  the  road.  The  piers  of  the  side  gates  are  connected  with 
the  parapets  of  the  bridge,  forming  a  continuous  structure. 
At  one  side  of  the  gateway  is  a  recess,  with  seats  and  a  drink- 
ing fountain.  The  total  cost  was  $5 1 ,000.  The  exposed 
surface  is  of  seam-faced  granite,  excepting  the  coping  and  cap 
stones,  which  are  red  granite.  The  soffit  of  the  arch  is  light 
colored  brick,  while  the  remainder  is  common  brick.  Shepley, 
Rutan  &  Coolidge  were  the  architects. 


145 


FIGURE  168.      Stony  Brook  Bridge,  Boston,  Mass. 

A  number  of  beautiful  bridges  have  been  constfucted 
during  the  last  few  years  in  the  city  of  Boston,  in  and  about 
its  park  system.  One  over  Stony  Brook,  in  the  Fenways, 
was  built  in  1891,  consisting  of  five  stone  arches  of  10  ft. 
span,  three  being  over  the  waterway  and  two  over  the 
footpaths  at  each  side.  The  bridge  is  85  ft.  wide  between 
parapets,  and  the  arches  are  supported  by  piers.  There  is 
at  each  end  a  flight  of  steps  from  the  sidewalk  on  the  bridge 
to  the  footwalks  beneath  it,  and  at  each  stairway  is  a 
drinking  fountain.  The  face  work  of  the  masonry  is  speckled 
brick  with  trimmings  of  Milford  granite.  The  barrel 
vaulting  is  lined  with  glazed  brick  of  different  colors,  in 
patterns.  The  total  cost  was  $40,000,  and  it  was  designed  by 
F.  L.  Olmstead  &  Company,  and  Walker  &  Kimball, 
architects. 


14? 


FIGURE  169.     Stockbridge,  Mass.,  Foot  Bridge 

One  of  the  lightest  concrete  bridges  ever  built  is  the  one 
at  Stockbridge,  over  the  Housatonic  river,  connecting  Laurel 
Hill  with  Ice  Glen.  It  has  a  clear  span  of  100  ft.,  rise  of 
10  ft.  a  total  length  of  124  ft.  and  a  7-ft.  roadway.  The 
crown  thickness  is  only  9  inches,  increasing  at  the  haunches  to 
30  inches.  It  is  reinforced  with  7-inch  curved  steel  beams 
28  inches  apart.  The  foundation  is  rock  and  the  whole 
structure  contains  only  22  cubic  yards  of  concrete.  It  was 
built  in  1894  at  a  cost  of  $1,475,  and,  after  completion'  was 
tested  with  a  load  of  25  tons. 


149 


FIGURE  170.      Lake  Park,  Milwaukee,  Foot  Bridge 

This  structure  carries  a  foot  path  in  Lake  Park,  Mil- 
waukee, across  a  ravine  59  ft.  deep.  It  is  located  quite 
near  to  the  pavilion  and  is  much  seen,  especially  in  the 
summer  time.  The  clear  span  is  1  1 8  ft.  between  abutments, 
rise  of  arch  is  18  ft.,  and  the  width  14  ft.  There  are  two 
reinforced  concrete  ribs,  12  inches  wide  and  54  inches  deep, 
with  an  inner  flange  9x9  inches  on  the  lower  side  of  the 
arch  ribs.  These  ribs  are  placed  12  ft.  apart  in  the  clear, 
and  support  the  spandrel  walls  which  carry  directly  the  6-inch 
reinforced  floor  slab.  At  distances  of  about  12  ft.  apart 
longitudinally,  there  are  cross  walls  and  struts  connecting  the 
main  arch  ribs,  and  between  them  is  a  double  system  of 
lateral  bracing  consisting  of  steel  angles  with  the  ends  securely 
fastened  into  the  concrete.  The  spandrel  walls  are  12  inches 
thick,  and  there  are  expansion  joints  at  each  end  adjoining  the 
abutments,  but  the  arch  ribs  and  abutments  are  monolithic. 
The  floor  is  cambered  8  inches  longitudinally  for  drainage, 
and  the  total  length  is  214  ft.  The  abutment  sides  are  con- 
nected with  cross  walls  which  carry  a  floor  slab  similar  to 
that  on  the  bridge.  Professor  Turneaure,  of  Madison,  was 
consulting  engineer  and  the  Newton  Engineering  Company, 
contractors. 


151 


FIGURE    171.      Union  Park,   Chicago,   Foot  Bridge 

Union  Park,  In  Chicago,  contains  a  fine  example  of  an 
ornamental  park  bridge,  the  sides  of  which  are  a  continuation 
of  the  wall  enclosing  the  pond.  It  is  apparently  more  of  a 
decorative  feature  than  for  use,  though  it  fulfils  both  condi- 
tions. It  was  built  in  1890  and  has  ornamental  lamps  and 
railing,  with  urns  containing  growing  plants  and  flowers  in 
the  summer  time. 


153 


FIGURE  172.      Boulder  Faced  Arch,  Washington 

This  is  a  segmental  concrete  arch  of  80  ft.  span,  crossing 
Rock  Creek.  The  rise  of  the  arch  is  15  ft.,  the  clear  roadway 
23  ft.,  and  total  outside  width  is  27  ft.  The  body  of  the 
arch  is  concrete,  reinforced  with  steel  on  the  Melan  system, 
and  the  face  boulders  of  the  arch  project  down  6  to  1 8  inches 
below  the  concrete  arch  soffit.  It  is  located  in  a  very 
beautiful  part  of  the  valley  and  is  greatly  admired.  The 
total  cost  was  $1  5,000,  and  it  is  was  designed  under  the  direc- 
tion of  Captain  L.  H.  Beach,  engineer  commissioner  of  the 
District  of  Columbia,  and  built  under  his  direction  and  that  of 
his  successor.  Col.  John  Biddle,  assisted  by  Captain  H.  C. 
Newcomer,    and   W.    J.    Douglas,    bridge   engineer. 


155 


Fig.  173 


Fig.   174 


FIGURE  173.      Yellowstone  Park  Concrete  Arch 

The  most  desirable  point  at  which  to  bridge  the  Yel- 
lowstone river  in  the  National  Park,  was  just  below  the 
Upper  Falls,  but  as  this  location  would,  to  some  extent, 
obscure  the  falls,  the  site  for  the  bridge  was  changed  to  a 
point  above  the  Upper  Falls  of  the  Yellowstone,  over  the 
rapids.  The  bridge  has  a  clear  span  of  120  ft.,  a  total 
length  of  160  ft.,  and  a  rise  of  15  ft.  The  roadway  at 
the  center  has  a  camber  of  2^  ft.,  and  the  clear  width  inside 
the  railing  is  1 5  ft.  At  the  center  the  bridge  floor  is  43 
ft.  above  the  water. 


FIGURE  174.      Eden  Park  Bridge,  Cincinnati,  Ohio 

Eden  Park  has  a  very  handsome  Melan  arch  with  a  span 
of  70  ft.  and  an  extreme  width  of  33  ft.  It  was  built  in  1 895 
and  crosses  Park  Ave.,  one  of  the  main  drives.  It  has  an 
18-ft.  roadway  and  two  walks  of  5  ft.  each.  The  rise  of  the 
arch  is  1 0  ft.  and  the  crown  thickness  is  1  5  inches,  increasing 
to  48  inches  at  the  springs.  It  is  reinforced  with  9-inch 
curved  steel  beams  spaced  3  ft.  apart.  An  effort  was  made 
to  have  the  whole  structure  ornamental,  for  the  soffit  of  the 
arch  is  paneled  and  the  balustrade  is  rich  in  detail,  with  heavy 
mouldings  and  panels  on  the  spandrels  and  abutments.  It 
was  designed  and  built  by  F.  von  Emperger  for  the  sum  of 
$7,130.  Bids  for  a  stone  bridge  ran  as  high  as  $12,000,  and 
it  is  probable  that  the  contract  price  did  not  include  the  entire 
cost  of  completion,  for  the  original  plans  showed  vases  and 
other  ornamentation  which  have  not  yet  been  provided. 


157 


Fig.   175 


Pig.  176 


FIGURES  175-176.      Bridge  at  Hyde  Park,  on  Hudson 

A  reinforced  concrete  arch  carries  the  driveway  ove' 
Crum  Elbow  Creek,  with  a  clear  span  of  75  ft.  The  con- 
crete railing  is  of  fine  design,  with  turned  balusters,  and  the 
elliptical  arch  and  curving  wing  walls  give  the  whole  a  very 
artistic  appearance. 


159 


FIGURE  177.      Como  Park  Foot  Bridge,  St.  Paul 

This  bridge  was  built  in  1903  to  provide  an  entrance  into 
Como  Park  for  the  passengers  of  the  Twin  City  Rapid 
Transit  Company.  It  has  a  clear  span  of  50  ft.,  with  a 
1 5-ft.  roadway.  A  very  neat  structure  was  desired  and,  in 
order  to  avoid  form  marks,  the  surface  of  the  centering  was 
covered  with  metal  lath  and  plaster,  before  placing  the  con- 
crete. The  length  between  abutment  piers  is  83  ft.,  and  total 
width  of  arch  17  ft.  8  inches.  The  arch  has  a  rise  of  1 2 
ft.  6  inches,  and  is  10  inches  thick  at  the  crown.  Span 
openings  over  the  spandrels  and  abutments  are  12  ft.,  and 
the  thickness  of  the  skew  back  piers  is  2  ft.  In  the  concrete 
are  five  latticed  steel  Melan  arch  ribs. 


16] 


FIGURE  178.      Newell  Avenue  Bridge,  New  York 

Located  in  the  Botanical  Gardens,  this  bridge  has  a  clear 
span  of  50  ft.  and  is  faced  with  granite,  though  the  body  of 
the  arch  is  of  reinforced  concrete  on  the  Emperger  system. 
The  outlines,  together  with  the  varied  kinds  of  surface  finish 
and  its  setting  in  the  foliage,  produce  a  satisfying  effect. 


163 


FIGURE  179.      South  Bridge,  Columbian  Park,  Lafayette 

The  foot  bridge  in  Lafayette,  shown  here,  has  a  clear 
span  of  40  ft.,  and  a  rise  of  4  ft.,  with  a  headroom  under- 
neath of  8  ft.  It  was  designed  in  1902  according  to  the 
Luten  patents,  and  has  a  length  of  56  ft.  and  a  clear  width  of 
6  ft.  The  crown  thickness  is  10  inches  and  the  arch  thrust 
is  resisted  by  tension  rods  embedded  in  concrete  beneath  the 
water. 


165 


FIGURE  180.      Park  Bridge,  Madison,  N.  J. 

Some  critics  have  stated  that  a  combination  of  two 
materials,  such  as  steel  and  stone,  in  one  structure,  is  offensive 
to  the  artistic  sense,  but  this  is  disproven  in  the  design  of  the 
park  bridge  at  Madison,  as  well  as  in  many  others.  The 
bridge  spans  two  railroad  tracks  and  has  an  opening  of  50 
ft.,  with  a  1 0-ft.  walk,  and  steps  of  stone  and  concrete  lead- 
ing up  to  the  deck  at  each  end.  The  object  was  to  construct 
the  center  part  of  steel,  and  to  produce  the  appearance  of 
an  arch  mounted  by  a  plate  iron  railing.  To  secure  this 
effect,  a  thin  fascia,  9  inches  wide  at  the  crown,  increasing 
to  2  feet  at  the  springs,  was  built  on  the  lower  external  girder 
faces.  The  girders  have  ornamental  cast-iron  copings,  and 
each  of  the  stone  piers  is  mounted  with  an  electric  globe. 
The  whole  is  surrounded  with  shrubs  and  flowers,  and  alto- 
gether presents  a  very  fine  appearance.  A  full  account  of 
this  bridge,  with  drawings,  may  be  found  in  The  Engineer 
of  London,  and  in  the  Engineering  News  of  New  York, 
in  1900. 


167 


i 


FIGURE   181.      Lion  Bridges,   Lake  Park,  Milwaukee 

Spanning  the  North  and  South  Ravines,  near  the  Gov- 
ernment Hghthouse  in  Lake  Park,  Milwaukee,  are  twin 
bridges  of  artistic  design.  Each  bridge  has  a  span  of  87 
feet,  and  the  total  cost  of  both  was  $36,500.  They  were 
designed  by  Oscar  Sanne,  and  built  during  the  year  1897. 
Each  bridge  has  six  two-hinged  steel  ribs,  supporting  a  floor 
of  beams  and  buckle  plates,  with  asphalt  roadways  and 
cement  sidewalks.  The  abutments  are  of  fine  coursed  ashlar, 
surmounted  with  a  Bedford  stone  railing.  Over  the  arches 
the  railing  is  of  ornamental  iron  and  steel,  while  at  the  ends 
are  ornamental  lamp  posts  supporting  clusters,  and  further 
decorated  with  figures  of  reclining  lions  on  pedestals. 


169 


FIGURE   182.      Bridge  in  Boston  Public  Gardens 

A  sight  which  is  very  famihar  to  New  England  people 
is  the  beautiful  little  suspension  bridge  in  the  Boston  Public 
Gardens.  It  is  difficult  to  say  whether  the  bridge  in  itself, 
or  its  beautiful  surroundings,  are  the  more  attractive.  The 
graceful  curves  of  the  cables,  passing  over  ornamental  stone 
towers,  together  with  the  stairways  and  electric  lamps  at 
either  end,  make  it  a  most  attractive  feature  of  the  Garden. 
In  the  summer  the  bridge  is  surrounded  with  a  great  variety 
of  plants  and  flowers,  and  is  perhaps  seen  and  appreciated 
by  more  people  than  any  other  work  of  a  similar  nature  in 
the  district.  The  lake  which  the  bridge  crosses  is  a  favorite 
resort  for  pleasure-seekers,  and  seats  near  the  water  edge 
beneath  the  trees  form  a  shady  retreat  for  pedestrians  in  the 
hot  days  of  summer. 


171 


FIGURE   183.      Garfield  Park  Suspension,   Chicago 

It  is  difficult  to  say  which  of  the  two  bridges  in  Garfield 
Park  is  the  more  attractive  in  design,  the  stone  arch  or  the 
suspension.  The  two  types  of  construction  add  varied  fea- 
tures to  this  beautiful  city  park. 


173 


FIGURE  184.      Pont-du-Gard,  at  Nimes,  France 

This  old  Roman  aqueduct  was  built  in  the  year  19  B.  C, 
to  supply  water  to  the  city  of  Nimes,  a  place  which  has 
many  remains  of  Roman  civilization.  It  was  built  during 
the  reign  of  Emperor  Augustus,  probably  under  the  direc- 
tion of  Agrippa.  There  are  three  stories,  the  lower  one  con- 
taining six  arches  and  the  second  story  eleven  arches  of  the 
same  span,  while  the  upper  or  third  has  thirty-six  smaller 
arch  openings  supporting  the  water  duct.  The  total  length 
of  the  upper  tier  is  885  feet  and  its  greatest  height  above 
water  is  1 60  feet.  In  the  year  1  743  extensive  repairs  were 
made,  and  the  lower  tier  of  arches  was  widened  enough  to 
carry  a  roadway  on  one  side,  so  the  present  structure  serves 
the  double  purpose  of  aqueduct  and  bridge,  the  length  of 
roadway  being  465  feet.  The  lower  arcade  was  originally 
made  of  four  separate  rings  side  by  side  and  not  bonded 
together,  and  the  second  tier  of  three  smaller  rings,  the 
original  width  of  the  lower  being  20  feet  9  inches,  and  the 
second  and  third  tiers  1 5  feet  and  1  1  feet  9  inches  respect- 
ively. The  largest  central  arch  over  the  Garden  River  has 
a  clear  span  of  80  feet  5  inches,  while  the  adjoining  ones 
on  either  side  vary  from  51  to  63  feet.  The  smaller  arches 
in  the  top  story  have  a  uniform  length  of  15  feet  9  inches, 
and  all  arches  are  semi-circular.  The  structure  carries  a 
single  waterway  4  feet  wide  and  4  feet  9  inches  high,  and  is 
built  of  cut  stones  tied  together  with  iron  clamps  without 
cement  excepting  in  the  water  channel  on  top.  It  is  said 
to  have  been  partly  destroyed  by  the  barbarians  in  the  fifth 
century,  but  was  soon  repaired. 


175 


FIGURE   185.      Karlsbrucke   over  the  Moldau  at  Prague 

Begun  in  1 348  by  Emperor  Charles  IV,  this  bridge  was 
not  completed  until  1 507.  There  are  sixteen  spans,  and 
over  the  piers  on  either  side  are  thirty  statues  and  groups  of 
saints.  The  total  length  of  the  bridge  is  1 ,855  feet,  and 
at  the  ends  are  gate  towers  with  unsymmetrical  roofs.  Not- 
withstanding the  unusually  heavy  piers  and  ice-breakers,  the 
bridge  was  seriously  damaged  by  Hoods  in  1 890,  but  has 
since  been  repaired.  The  large  bronze  statue  was  erected 
to  the  memory  of  St.  John  Nepomuc,  patron  saint  of  Bo- 
hemia, to  visit  which  thousands  of  pilgrims  annually  come. 
It  is  said  that  St.  John  had  received  confidential  information 
from  the  Empress,  and  upon  refusing  to  betray  these  secrets, 
the  Emperor  caused  him  to  be  thrown  from  the  bridge  and 
drowned.  The  statue  to  his  memory  was  therefore  placed 
so  that  it  might  overlook  the  scene  of  his  death.  It  is  related 
further  that  Ferdinand  II,  after  defeating  the  Protestant  King 
of  Bohemia  in  the  battle  of  White  Mountain,  near  Prague, 
in  1 620,  caused  twenty-seven  Bohemian  noblemen  to  be 
beheaded  and  their  heads  hung  m  iron  cages  from  the  tower. 


177 


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FIGURE   186.      Bridge  of  Alcantara  at  Toledo 

Several  fine  old  bridges  at  Toledo,  Spain,  still  remain 
after  the  lapse  of  many  centuries.  The  one  illustrated  dates 
from  997  A.  D.,  and  is  still  in  good  condition.  The  arches 
have  spans  of  93  and  52  feet  and  are  semi-circular,  indicating 
Roman  origin.  Of  the  two  portal  towers,  the  left  one  with 
battlements  seems  to  symbolize  strength  and  defence,  while 
the  other  one  is  lighter  and  more  highly  ornamented.  The 
small  Moorish  arch  and  many  other  features  are  quite  unex- 
plainable  in  this  age.  Two  retreats  are  bracketed  out  on  each 
side  of  the  long  abutment,  and  above  the  triangular  cutwaters 
are  two  other  retreats. 


i7y 


FIGURE    187.      The   Rialto,    Venice 

A  bridge  which  is  perhaps  more  widely  known  than  any 
other  is  the  Rialto  at  Venice.  It  crosses  the  Grand  Canal 
and  was  built  during  the  years  1588  to  1591,  from  designs 
by  Antonio  da  Ponte,  though  other  designs  are  said  to  have 
been  prepared  for  it  by  Michael  Angelo  and  Palladio.  Re- 
ferring to  the  form.er,  the  Encyclopaedia  Britannica  says: 
"Erroneous  statements  are  often  made  that  this  bridge  was 
built  from  a  design  by  Michael  Angelo.  The  mistake  has 
arisen  from  the  misinterpretation  of  a  passage  in  the  works 
of  Vasari."  The  bridge  has  a  clear  span  of  about  95  feet 
with  a  rise  of  25  feet,  a  total  length  of  1  58  feet  and  width 
of  72  feet.  On  the  roadway  are  two  rows  of  shops  with  a 
passageway  between  them.  There  are  six  shops  in  each 
row  on  each  side  of  the  center,  or  twenty-four  in  all.  In 
the  middle  of  the  bridge  is  an  open  passage  connecting  the 
roadway  with  the  walks,  the  whole  arrangement  forming  an 
arcade.  The  regular  footways  are  on  the  outside  and  are 
carried  on  projecting  brackets.  As  the  grade  of  the  floor 
is  quite  steep,  the  walks  are  provided  with  marble  steps,  and 
are  enclosed  with  ornamental  balustrades  of  beautiful  design. 
The  arch  ring  and  spandrels  are  ornamented  on  the  face  with 
figures  of  angels,  and  there  are  tablets  with  inscriptions.  The 
form  of  the  arch  is  segmental,  being  about  one-third  of  a 
circle,  and  the  material  is  white  marble.  Steps  at  either  end 
of  the  bridge  lead  up  from  the  foot  walks  along  the  canal, 
and  the  arrangement  of  arches  on  the  rising  grade,  together 
with  the  central  passageway  and  arch  above  it,  present  a 
general  effect  of  beauty  and  harmony. 


181 


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FIGURE    188.      London  Bridge 

The  present  London  Bridge  was  constructed  during 
the  years  1 82 1  to  1  830,  and  replaced  the  old  one  that  was 
lined  with  shops  and  houses.  The  bridge  is  a  fine  example 
of  the  highest  class  of  stone  arch  construction.  It  has  five 
elliptical  arches,  the  center  one  being  1  52  feet  long,  the  two 
adjoining  ones  140  feet,  and  the  end  ones  130  feet.  The 
face  work  is  of  granite.  Its  entire  length  is  928  feet,  and 
it  is  estimated  that  120,000  foot  passengers  and  25,000 
vehicles  cross  it  daily.  The  design  was  prepared  by  the 
elder  John  Rennie,  and  it  was  constructed  under  the  direc- 
tion of  his  sons,  John  and  George  Rennie.  The  cost  was 
425,000  pounds  sterling.  During  the  years  1902  to  1905, 
the  original  width  of  54  feet  was  increased  by  1  1  feet,  at  an 
additional  cost  of  $500,000,  under  the  direction  of  E.  Crutt- 
well  and  Sir  Benjamin  Baker,  engineers. 


FIGURE  189.      Cabin  John  Bridge,  Washington 

For  many  years  Cabin  John  Bridge,  spanning  Rock 
Creek  at  Washington,  held  the  record  for  being  the  longest 
stone  arch,  though  it  has  since  been  exceeded  by  those  at 
Luxemburg,  278  feet;  at  Plauen,  295  feet;  and  Salcano, 
There  are  also  several  concrete  bridges  either  completed  or 
under  construction  with  longer  spans.  This  bridge  carries 
a  road  and  the  aqueduct  for  the  city  of  Washington,  and  was 
built  under  the  direction  of  Gen.  M.  C.  Meigs,  during  1857 
to  1864.  The  span  is  220  feet,  rise  57  feet,  and  the  center 
crown  radius  134  feet,  the  roadway  being  101  feet  above 
the  water.  The  material  of  the  arch  ring  is  granite,  with 
spandrels  of  sandstone,  the  ring  being  4  feet  deep  at  the 
crown  and  6  feet  at  the  springs.  Backing  for  some  distance 
beyond  the  arch  ring  is  laid  with  radial  joints,  thus  adding 
greatly  to  its  strength.  The  arch  is  a  segment  of  1  10  degrees 
and  the  entire  work  is  very  simple  in  charactei-.  The  bridge 
has  a  total  width  over  parapets  of  20  feet,  and  the  flatness 
of  the  face  is  relieved  by  two  projecting  courses. 


185 


FIGURE   190.      Croton  Aqueduct  Bridge   (High  Bridge),  New  York  City 

The  Manhattan  water  supply  is  brought  into  the  city  in 
pipes  carried  on  a  series  of  arches  known  as  High  Bridge. 
At  high  water  the  Harlem  River  has  a  width  of  620  feet, 
and  the  demands  of  navigation  made  it  imperative  to  provide 
a  clear  headroom  of  100  feet  beneath  the  bridge,  with  open- 
ings not  less  than  80  feet  in  width.  There  are,  therefore,  over 
the  water,  eight  spans  of  80  feet  each,  with  six  spans  of  50 
feet  at  the  end  next  the  mainland,  and  one  of  30  feet  at  Man- 
hattan Island.  The  total  length  is  1 ,460  feet  and  the  height 
above  high  water  is  116  feet.  The  width  over  parapets  is 
21  feet,  and  the  faces  of  spandrels  and  piers  batter  out  on 
each  side  at  the  rate  of  one  inch  in  4  feet.  It  originlly  carried 
only  two  lines  of  cast-iron  water  pipe  36  inches  in  diameter, 
but  a  third  pipe  90  inches  in  diameter  was  added  later.  The 
deck  carries  a  driveway  and  two  walks,  which  are  guarded 
by  light  but  ornamental  railings.  Above  the  arches  are  orna- 
mental belt  courses  and  a  coping  on  corbels,  and  at  the  piers 
are  pilasters  extending  from  the  springs  to  the  coping,  the 
whole  presenting  a  very  satisfactory  effect.  It  was  designed 
under  the  direction  of  John  B.  Jervis,  Chief  Engineer  of  the 
Croton  Aqueduct,  and  built  during  the  years  1837  to  1842, 
at  a  cost  of  $737,800. 


]87 


FIGURE    191.      Echo    Bridge,    Newton 

This  stone  bridge  was  built  in  1 876,  under  the  direction 
of  Chief  Engineer  Fitzgerald,  by  the  Boston  Water  Com- 
mission, to  carry  a  conduit  across  the  Charles  River.  It  has 
one  span  of  129  feet  and  42  feet  rise,  one  span  of  34  feet, 
and  four  of  37  feet,  the  coping  being  78  feet  above  the  river. 
It  is  within  the  Metropolitan  Park  System  and  is  a  familiar 
sight  to  Boston  residents,  especially  in  the  summer  season^, 
The  illustration  shows  the  details  of  the  largest  span,  the 
smaller  ones  bemg  at  one  end.  When  the  whole  bridge  is 
seen,  its  unsymmetrical  arrangement  is  not  pleasing,  but  the 
smaller  spans  are  so  obscured  by  foliage  that  the  large  arch, 
onlv,  is  evident. 


189 


FIGURE    192.      Wissahickon   Railroad  Bridge 

Prominently  situated,  crossing  over  Wissahickon  Creek 
where  it  flows  into  the  Schuylkill  River,  is  the  Philadelphia- 
and  Reading  railroad  bridge,  which  can  be  seen  for  a  dis- 
tance of  a  mile  or  more  up  and  down  the  river  and  from 
either  bank.  It  was  erected  in  1881,  from  the  designs  of 
C.  W.  Buchholz,  Chief  Engineer  for  the  railroad  company. 
There  are  five  spans  of  70  feet  each,  and  23  feet  rise,  the 
thickness  of  arch  rings  being  3  feet,  and  pier  thickness  at 
springs  9-^  feet.  The  width  of  the  bridge  is  28  feet  for  two 
tracks,  while  the  total  length,  including  the  four  1 0-foot 
arches,  two  in  each  abutment,  is  5 1 0  feet.  The  deck  is  80 
feet  above  the  drive  beneath  it  and  1 03  feet  above  the 
foundations.  It  contains  15,400  cubic  yards  of  Talcose 
slate  masonry,  and  cost  $275,000,  The  valley  crossed  is  a 
part  of  the  Fairmount  Park  system. 


191 


FIGURE    193.       Interlaken   Bridge,    Minneapolis 

Spanning  two  lines  of  electric  car  tracks,  with  clear  open- 
ing of  38  feet  and  side  walls  82  feet  long,  is  this  bridge 
built  for  the  Board  of  Park  Commissioners  of  Minneapolis. 
It  supports  a  40-foot  roadway  with  a  10-foot  walk  at  one 
side  and  a  10-foot  bicycle  path  at  the  other,  making  an 
extreme  width  of  63  feet.  The  arch  ring  of  the  face  walls 
and  the  skewbacks  and  copings  are  of  Kettle  River  sand- 
stone, but  all  other  face  work  is  blue  limestone.  The  body 
of  the  arch  is  the  Melan  system  of  concrete  steel  construc- 
tion. It  is  the  work  of  W.  S.  Hewett,  contractor,  and  Harry 
Jones,  architect. 


193 


FIGURE    194.      Chatsworth  Bridge 


This  bridge  is  located  on  one  of  the  private  estates  of 
England,  with  statues  on  the  piers  above  the  water. 


11.;: 


Fig.   195 


FIGURE   195.      Proposed  Hudson  Memorial  Bridge 

It  has  been  proposed  to  erect  on  an  extension  of  River- 
side Drive  in  New  York  City  a  memorial  bridge  over  Spuyten 
Duyvil  Creek,  to  commemorate  the  discoveries  and  explora- 
tions of  Henry  Hudson,  The  design  accepted  by  the  Munici- 
pal Art  Commission  of  New  York  is  illustrated.  Several 
others  of  great  merit  were  prepared  and  submitted,  the  reason 
for  their  rejection  being  that  all  in  steel  were  unsuited  for  a 
great  memorial.  In  this  design  there  would  be  one  span  with 
a  clear  span  of  703  feet,  and  seven  other  semi-circular  spans 
with  clear  lengths  of  108  feet,  the  total  length  of  the  struc- 
ture being  2,840  feet.  The  main  arch  span  has  a  rise  of  I  77 
feet,  and  is  to  contain  a  large  amount  of  steel,  used  not  as 
concrete  reinforcement  ordinarily  is  to  resist  tensile  stresses, 
but  rather  to  assist  in  resisting  the  compressive  stresses  and 
thereby  reduce  the  amount  of  masonry.  The  arch  with 
crown  thickness  of  1  5  feet  is  to  support  two  decks,  the  upper 
one  with  a  50-foot  roadway  and  two  1  5-foot  walks,  and  the 
lovver  one  70  feet  wide  for  four  lines  of  electric  railway, 
though  it  is  intended  to  omit  the  construction  of  the  lower 
deck  when  first  building.  The  design  provides  for  a  clear 
headroom  of  1 83  feet  under  the  main  arch.  The  principal 
piers  are  to  be  180  feet  wide,  and  the  estimated  cost  of  the 
whole  structure  is  $3,800,000.  The  design  was  prepared 
by  the  Bridge  Department  of  the  City  of  New  York,  C.  M. 
Ingersol,  Chief  Engineer,  L.  S.  Moisseiff,  engineer  in  charge, 
Wm.  H.  Burr,  consulting  engineer,  and  Whitney  Warren, 
archstect. 


197 


FIGURE  196.      Walnut  Lane  Bridge,  Philadelphia 

Over  this  bridge  Walnut  Lane  crosses  the  Wissahickon 
valley  at  a  height  of  147  feet  above  the  river  bed,  connecting 
Roxborough  and  Germantown,  two  residential  suburbs  of 
Philadelphia.  When  first  completed  it  was  the  largest  con- 
crete bridge,  having  a  clear  span  of  233  feet.  It  consists  of 
two  separate  arch  rings,  1 8  feet  wide  at  the  crown,  increas- 
ing to  2 1  ^  feet  at  the  springs,  and  at  the  crown  the  rings  are 
separated  by  a  space  of  1  6  feet.  The  main  arch  is  an  approx- 
imate ellipse  with  a  rise  of  73  feet,  and  carries  ten  cross- 
walls  which  support  the  floor  system,  but  there  are  also  five 
semi-circular  approach  arches  with  clear  spans  of  53  feet.  The 
roadway  is  40  feet  wide,  with  a  10-foot  walk  at  each  side. 
The  whole  structure  is  of  solid  concrete  reinforced  only  m 
minor  parts.  The  surface  finish  is  rough,  somewhat  similar  to 
pebble  dash,  but  of  coarser  grain,  and  the  exposed  surface 
shows  stone  chips  of  not  over  -|  inch  size,  formed  by  washing 
before  the  cement  was  hardened.  The  total  length  of  bridge 
over  all  is  585  feet,  and  cost  $259,000.  George  S.  Web- 
ster v/as  Chief  Engineer  and  Henry  H.  Quimby,  Bridge 
Engineer. 


199 


■MJm 


FIGURE   197.      Proposed  Potomac  Memorial  Bridge  No.  2 

On  this  design  there  is  but  one  deck,  with  no  provision 
for-  car  tracks.  It  is  60  feet  wide  and  the  total  length  of 
open  bridge  is  3,400  feet.  In  the  central  part  are  six  seg- 
mental masonry  arches,  1 92  feet  in  clear  length,  with  a 
double  leaf  bascule  draw  of  1  70  feet  in  the  center.  The 
Washington  approach  has  twelve  semicircular  masonry  arches 
of  60  foot  span  and  550  feet  of  embankment,  and  the  Arling- 
ton approach  fifteen  similar  spans  and  1 ,350  feet  of  embank- 
ment. All  work  is  granite  faced,  with  reinforced  concrete 
body,  and  the  estimated  cost  is  $3,680,000. 


201 


.^^a^^'J 


FIGURE   198.      Proposed  Potomac  Memorial  Bridge,  Washington,   D.   C. 
Washington,   D.   C. 

This  is  a  modification  of  Mr.  Burr's  plan  No.  2  (Fig. 
197)  for  a  bridge  over  the  Potomac  river  at  Washington, 
with  the  central  towers  of  his  Plan  No.  1  substituted  for  those 
previously  shown.  In  all  other  respects  the  plan  is  identically 
the  same  as  that  shown  in  Fig.  1 97,  and  is  the  design  as  finally 
accepted. 


203 


FIGURE    199.      Rocky   River   Bridge,    Cleveland 

One  of  the  largest  masonry  spans  in  America  is  over  Rocky 
River  on  Detroit  Avenue,  at  Cleveland,  Ohio.  The  central 
span  is  280  feet  and  the  five  terminal  spans  are  44  feet 
each,  making  a  total  length  of  780  feet.  The  width  over 
railings  is  60  feet,  the  roadway  being  40  feet  and  the  two 
sidewalks  8  feet  each.  The  main  span  consists  of  two  sepa- 
rate arch  rings  1 8  feet  wide  at  the  crown  and  1 6  feet  apart, 
by  which  the  deck  is  carried  on  cross  spandrel  walls.  The 
roadway  is  94  feet  above  low  water,  and  the  pavement  is  of 
brick  with  two  lines  of  track  for  heavy  suburban  cars.  Be- 
neath the  floor  are  two  subway  chambers  3  by  1  1  feet,  for 
pipes  and  wires.  The  main  arch  rings  contain  no  steel  rein- 
forcing, as  calculations  showed  that  tension  cannot  occur  in 
any  part  of  the  arch.  The  sidewalks  project  about  5  feet 
over  the  face  walls,  and  are  supported  on  brackets.  The 
whole  structure  is  of  concrete  and  is  quite  similar  to,  and  47 
feet  longer  than,  the  Walnut  Lane  bridge. 


205 


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i 

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ll 

^'",         '   ^,                 V   ^_     ,..-..* ^  *  ''■"     ■'    ■  ■■"■'-^??*-  ~.^'-^  ,■■-:■                              ^ 

'"'^■Si^ll 

FIGURE    200.      Big   Muddy   River   Bridge 

The  Big  Muddy  River  bridge  at  Grand  Tower  in  South- 
ern IIHnois,  carries  two  tlracks  of  the  IlHnois  Central  Railroad, 
and  was  completed  in  1902,  after  a  period  of  twenty  months 
in  construction.  It  replaced  an  old  three-span  metal  bridge 
with  piers  9  to  1 0  feet  thick,  and  was  renewed  without  inter- 
fering with  the  operation  of  trains.  Preliminary  estimates 
showed  that  a  new  steel  bridge  with  solid  floor  would  cost 
$125,700,  or  slightly  more  than  the  one  selected  in  solid 
concrete.  In  comparison  with  reinforced  concrete  the  latter 
showed  no  economy,  and  much  delay  might  have  resulted  in 
waiting  for  reinforcing  steel.  The  bridge  contains  three 
arches  of  140  feet,  with  true  ellipses  for  the  intrados,  and 
semi-minor  axes  of  30  feet,  though  the  rise  on  line  of  pres- 
sure is  somewhat  less.  Open  spandrels,  though  costing  more 
than  solid  ones  on  so  flat  an  arch,  were  preferred  in  order 
to  decrease  the  load  on  the  foundation  piles,  and  light  metal 
reinforcing  frames  in  the  spandrels  were  used  for  convenience 
in  erection.  The  bridge  is  463  feet  long,  and  the  width  is 
32  feet  extreme,  or  26  feet  inside  the  copings,  the  crown 
thickness  of  the  arch  being  7  feet.  Piers  are  22  feet  high 
to  the  springs,  and  the  new  ones,  which  are  22-^  feet  thick, 
were  built  around  the  old  ones  as  centers.  The  spandrel 
arches  have  a  length  of  13  feet.  Provision  was  made  for 
expansion,  but  after  completion  none  was  found.  It  con- 
tains 12,000  cubic  yards  of  concrete,  or  one  yard  for  each 
square  foot  of  roadway,  and  1 50  tons  of  steel.  The  final 
cost  was  $124,900,  equal  to  $10  per  square  foot  of  floor, 
or  $5.40  per  cubic  yard  of  concrete.  The  bridge  is  quite 
similar  to  one  previously  built  at  Verdun,  France. 


207 


FIGURE  201.      Double  Track  Railroad  Bridge 

On  the  line  of  the  Cleveland,  Cincinnati,  Chicago  and 
St.  Louis  Railroad,  between  Terre  Haute  and  Indianapolis, 
Indiana,  is  an  interesting  railroad  structure  of  concrete  with 
three  spans  of  75  feet  in  the  clear.  W.  M.  Dunne  was  Chief 
Engineer. 


209 


FIGURE   202.      Zanesville,   Ohio,    Y   Bridge 

The  concrete  bridge  across  the  Muskingum  and  Licking 
Rivers  at  Zanesville  is  the  fourth  one  on  the  site,  former 
ones  having  been  either  wrecked  or  removed.  In  spanning 
the  two  rivers  at  their  junction,  it  was  necessary  to  build  the 
bridge  with  three  arms  meeting  at  the  center  pier.  The  east 
arm  is  400  feet  long  with  three  spans  of  122  feet;  the  west 
arm  is  250  feet  long  with  two  spans  of  1 22  and  90  feet, 
while  the  north  arm  is  250  feet  with  three  spans  of  81  feet. 
The  foundation  in  all  cases  rests  on  solid  shale  rock.  Shal- 
low arches  were  used  on  account  of  the  small  distance 
between  the  desired  floor  grade  and  the  high-water  level. 
It  has  a  30-foot  roadway  and  two  6-foot  walks,  making  a 
total  width  inside  of  railings  of  42  feet.  The  contractors 
were  Bates  and  Rogers  of  Chicago,  and  the  engmeers  The 
Osborne  Engmeermg  Company  and  E.  J.  Landor. 

FIGURE   203.      Washington    Street   Bridge,    Dayton,    Ohio 

Washington  Street  Bridge  was  the  third  one  of  the  kind 
built  by  the  city  over  the  Great  Miami  River.  It  replaced  an 
old  steel  bowstring  truss  bridge  that  had  become  too  light 
for  the  heavy  car  travel.  It  was  erected  during  the  years 
1 905-06,  by  F.  J.  Cullen,  contractor,  from  plans  prepared 
by  the  Concrete  Steel  Engineering  Company.  It  contains 
seven  spans  of  the  following  dimensions: 

One  center  span,  90  feet;  rise,   I  1.5  feet. 

Two  adjacent  spans,  86  feet;    rise,  10.5  feet. 

Two  next  spans,  80  feet;    rise,  9.3  feet. 

Two  end  spans,  74  feet;    rise,  8  feet. 

The  total  length  face  to  face  of  abutments  is  620  feet. 
It  is  built  on  the  Melan  patents,  with  steel  reinforcing  ribs  3 
feet  apart.     Its  total  cost  was  $122,000. 


211 


FIGURE   204.      Jamestown  Exposition  Bridge 

The  United  States  Government  built  a  bridge  at  the 
Jamestown  Exposition  of  1907,  to  connect  the  outer  ends 
of  two  piers.  It  is  of  reinforced  concrete,  with  a  clear  span 
of  151  feet  and  26  feet  rise,  and  is  36  feet  wide,  for  pedes- 
trians only.  It  consists  of  two  reinforced  concrete  ribs  carry- 
ing the  roadway  on  four  longitudinal  walls,  the  ascent  of  the 
road  being  made  on  a  series  of  steps  and  landings.  The 
abutments  are  cored  out  and  each  one  rests  on  twenty-six 
plumb  and  126  batter  piles.  The  design  was  made  and  exe- 
cuted by  the  Scofield  Company  of  Philadelphia. 


2V6 


FIGURE    205.      Marion    County,    Highway    Bridge 

This  reinforced  concrete  bridge,  with  its  rustic  parapet 
walls,  was  built  on  the  Melan  system,  with  a  span  of  32  feet. 
It  is  one  of  many  small  highway  bridges  built  throughout 
the  middle  West  to  carry  country  roads  over  small  streams 
and  ravines,  the  rustic  finish  being  quite  suitable  for  rural 
districts  or  wooded  parks. 


215 


FIGURE  206.      Newark,  N.  J.,  Park  Bridge 

In  Branch  Brook  Park  at  Newark  there  is  a  bridge  of 
reinforced  concrete,  carrying  Park  Avenue  over  a  waterway, 
the  side  view  of  which  is  shown.  The  span  of  arch  is  132 
feet,  clear  width  inside  of  raihng  70  feet,  and  total  length 
244  feet.  It  has  a  40-foot  roadway  and  two  1 5-foot  walks 
with  a  clearance  underneath  of  22  feet,  and  contains  6,200 
cubic  yards  of  concrete  and  1 24  tons  of  steel.  The  total  cost 
without  pavement  was  $84,000.  Work  was  carried  on  from 
August,  1904,  to  January,  1905,  under  the  direction  of  the 
Park  Commissioners  of  Essex  County.  A.  M.  Reynolds, 
engineer;  Babb,  Cook  &  Willard,  architects. 


21/ 


FIGURE   207.      Grand   Rapids,    Concrete   Bridge 

This  is  a  good  example  of  the  best  American  practice  in 
concrete  construction.  It  has  a  roadway  64  feet  wide.  Of 
the  five  spans,  the  center  one  is  87  feet,  the  two  adjoining 
ones  83  feet,  and  the  two  end  spans  79  feet  each.  It  was 
designed  by  Wm.  F.  Tubesing,  bridge  engineer  for  L.  W. 
Anderson,  City  Engineer,  and  was  constructed  in  1904  by 
J.  P.  Rusche,  contractor,  of  Grand  Rapids. 


5iiy 


FIGURE    208.      White    River   Bridge    at   Morris   Street,   Indianapolis 

Five  spans  of  Melan  concrete  arches  ranging  in  length 
from  90  to  110  feet  compose  this  bridge,  the  exposed  parts, 
excepting  arch  soffits,  being  faced  with  stone.  It  presents  a 
very  neat  appearance. 


^21 


FIGURE  209.      Northwestern  Avenue  Bridge,  Indianapolis 

This  is  one  of  the  bridges  recently  built  by  the  city  of 
Indianapolis.  It  has  three  spans  74  feet  long  each,  on  the 
Melan  system  of  reinforced  concrete,  the  exposed  parts  of 
piers  and  arches  being  faced  with  stone.  Above  the  piers 
are  semi-columns  carried  up  to  support  retreats.  It  crosses 
Fall  Creek  and  is  somewhat  similar  to  those  at  Illinois  and 
Meridian  Streets,  excepting  that  Northwestern  Avenue  bridge 
has  a  more  ornamental  balustrade. 


FIGURE  210.      White  River  Bridge  at  Emerichsville,  Ind. 

There  are  few  bridges  in  America  with  entrance  arches, 
but  this  has  a  fine  archway  over  the  roadway  at  the  end 
adjoining  the  park.  The  spans  have  a  length  of  110  feet 
each  and  the  three  arches  are  ornamented  on  the  face  and 
spandrels  with  panels  and  elaborate  mouldings  above  the 
piers.  With  adjoining  landscape  and  boulevards,  it  would 
be  a  fine  example  of  ornamental  work. 


225 


FIGURE  211.      Topeka  Bridge  over  the  Kansas  River. 

An  interesting  example  of  concrete  construction  is  at 
Topeka,  across  the  Kansas  River.  It  has  one  span  of  1 25 
feet,  two  of  1  1 0  feet,  and  two  of  97|^  feet,  and  at  the  time 
of  buildmg  was  the  largest  one  of  concrete-steel  in  existence, 
though  it  has  since  been  surpassed  by  several  others.  The 
roadway  is  26  feet,  and  the  two  walks  7  feet  each,  making  a 
total  width  of  40  feet.  It  was  built  during  the  years  1896- 
97,  and  cost  complete  $150,000.  The  twelve  lines  of  steel 
reinforcing  ribs  are  3  feet  apart  on  centers.  Keepers  and 
Thacher  were  the  designers,  and  H.  V.  Hinckley,  resident 
engineer. 


227 


FIGURE   212.      Wayne  Street   Bridge,   Peru,    Ind. 

The  Wayne  Street  bridge  was  built  under  the  direction 
of  the  County  Commissioners  of  Miami  County,  in  the  six 
months  from  June  to  December,  1 905.  It  has  seven  spans, 
the  center  one  being  100  feet  and  the  others  95,  85,  and  75 
feet,  respectively,  towards  the  ends.  The  roadway  is  30 
feet  wide,  with  a  clearance  above  low  water  of  24  feet. 
The  thickness  of  arch  rings  vary  from  21  to  25  inches  at  the 
crown,  and  the  rise  from  13  to  15  feet.  Piers  are  6  feet 
thick  at  the  springs,  and  stand  on  bed  rock.  The  bridge  con- 
tains 5,200  cubic  yards  of  concrete  and  50  tons  of  steel 
reinforcing.  In  January,  1907,  it  had  a  severe  test,  when 
the  Wabash  River  rose  to  within  five  feet  of  the  soffits,  and 
the  approaches  at  both  ends  were  under  two  feet  of  water,  but 
no  injury  was  sustained. 


229 


FIGURE   213.      Green   Island   Bridge,   Niagara  Falls 

Crossing  from  Green  Island  to  the  American  side  of  the 
Niagara  River,  over  the  main  channel,  is  a  three-span  rem- 
forced  concrete  arch  bridge  of  the  Melan  type,  with  stone 
facing.  It  stands  over  the  rapids,  w^here  water  runs  at  a 
velocity  of  24  miles  per  hour,  and  just  below  it  are  the 
American  Falls.  It  has  a  center  span  of  1  1 0  feet  and  two 
side  spans  of  100  feet  each,  and  for  arches  of  so  flat  a  rise 
the  design  is  quite  artistic.  The  stone  arch  rings  and  facing, 
together  with  the  belt  course  of  different  material,  above  the 
crown,  and  the  smooth  stone  coping,  as  well  as  the  semi- 
columns  at  the  piers,  all  unite  to  produce  a  pleasing  effect. 


231 


I 


FIGURE    214.       Bridge     Over     Niagara    River,     from    Green     Island    to 

Goat   Island. 

This  is  smaller  than  the  Green  Island  bridge  illustrated 
on  page  231,  the  center  span  being  55  feet  and  the  end  ones 
each  50  feet  6  inches. 


233 


FIGURE   215.       Maumee   River  Bridge  at   Waterville,   Ohio 

This  structure  is  comprised  of  twelve  spans  of  reinforced 
concrete,  with  arches  varying  in  length  from  75  to  90  feet, 
and  rise  of  about  25  feet.  The  total  length  is  1,200  feet 
and  the  deck  is  45  feet  above  low  water,  with  a  width  of  16 
feet  in  the  clear.  It  was  erected  in  1908,  to  carry  a  single 
track  of  Lima  and  Toledo  Traction  Company,  which  was 
built  for  the  Ohio  Electric  Railway  Company  of  Cincin- 
nati. The  bridge  crosses  the  Maumee  River  fifteen  miles 
southwest  of  Toledo,  and  contains  9,200  cubic  yards  of  con- 
crete and  1 00  tons  of  reinforcement.  Piers  stand  on  bed 
rock  and  are  1 0  feet  thick  at  the  springs.  It  was  designed 
by  The  National  Bridge  Company,  Daniel  B.  Luten,  Presi- 
dent, the  contract  price  being  $77,000. 


i?;?5 


FIGURE  216.      Concrete-Steel  Bridge  at  Derby,  Conn. 

The  three  spans  are  each  72  feet  in  the  clear,  and  the 
bridge  is  54  feet  wide.  The  parapet  is  a  soHd  concrete  slab 
paneled  on  the  faces. 


'SM 


FIGURE   217.      Hudson   Memorial,  Design  No.   1 

A  design  for  the  Hudson  Memorial  bridge  made  by 
Boiler  and  Hodge  contemplates  the  use  of  a  400-foot  steel 
arch,  but  the  plan  was  rejected  by  the  Municipal  Art  Com- 
mission of  New  York,  as  construction  m  steel  was  considered 
unsuitable  for  a  great  memorial  structure.  The  drawmgs 
show  three  terminal  spans  at  the  south  end  and  five  at  the 
north,  all  80-foot  semi-circular  arches.  The  massive  piers 
are  shown  with  interior  chambers,  the  two  principal  ones 
being  continued  above  the  deck  in  monumental  arches  over 
the  roadway.  The  masonry  could  be  carried  out  in  either 
stone  or  concrete,  or  a  combination  of  the  two  materials. 


Fis.   218 


FIGURE  218.      Hudson  Memorial,  Design  No.   2 

Another  design  for  this  memorial  bridge  provides  a  main 
span  of  825  feet  in  length,  framed  with  two  pairs  of  three- 
hinged  steel  arch  trusses,  carrying  a  roadway  100  feet  in 
width  and  1  70  feet  above  the  water.  The  length  as  planned 
is  2,500  feet.  Seven  masonry  approach  spans  of  90  feet  are 
shown,  and  two  through  the  abutments  with  clear  spans  of 
65  feet  and  a  height  of  1 20  feet.  It  was  the  intention  of  the 
designer  to  erect  a  statue  of  Hudson  on  a  massive  pedestal 
in  the  plaza  at  the  southern  end,  but  this  feature  does  not 
show  in  the  view.  The  design  was  prepared  by  Messrs. 
Boiler  and  Hodge  of  New  York. 


241 


FIGURE  219.      Grant  Memorial  Bridge,  Washington 

Several  designs  were  prepared  in  1  886-87  by  Paul  Pelz, 
architect,  and  Capt.  T.  W.  Symonds,  engineer,  for  a  Grant 
Memorial  Bridge  across  the  Potomac  River,  which  are  among 
the  finest  ones  produced  in  this  or  any  other  country.  The 
proposed  site  was  midway  between  the  Long  Bridge  and 
the  aqueduct,  and  Congress  proposed  an  appropriation  of 
$500,000  to  begin  the  work,  but  it  was  postponed.  One 
of  these  plans  has  two  central  towers  230  feet  above  the 
water  and  1 60  feet  apart,  with  a  double  bascule  span  between 
them  and  a  series  of  steel  deck  arch  spans  at  each  side.  The 
roadway  is  40  feet  wide  with  10-foot  sidewalks,  and  at  the 
piers  are  minor  towers.  The  design  as  a  whole  is  well  con- 
ceived and  strong,  and  harmonious  in  all  its  parts,  the  details 
bemg  in  Mediaeval  style  of  architecture. 


243 


FIGURE    220.      Grant    Memorial    Bridge,    Washington,    No.    2 

Another  design  for  the  same  project  as  the  previous  one 
was  made  in  1887  by  Mr.  Pelz,  in  classic  style,  with  two 
triumphal  arches  mounted  with  equestrian  groups  in  bronze, 
and  lower  towers  at  the  sides,  with  arched  openings.  The 
details  of  the  columns  are  Corinthian,  as  are  also  those  on 
the  minor  towers  nearer  the  end.  These  great  arches  on  their 
heavy  piers,  with  rounded  ice-breakers,  form  a  massive  cen- 
tral feature  and  mark  the  position  of  the  bascule  span  and 
channel.  The  materials  used  are  steel  and  granite,  as  in  the 
previous  design,  and  the  metal  arches  are  of  nearly  the  same 
style.  It  is  to  be  greatly  regretted  that  such  designs  as  these, 
reflecting  so  much  credit  upon  the  aesthetic  phase  of  bridge 
building  in  America,  should  not  come  to  fruition,  as  have 
others  in  Europe. 

FIGURE  221.      Clifton  Highway  Arch,   Niagara  Falls 

The  Clifton-Niagara  bridge  over  the  Niagara  River, 
1,000  feet  below  the  Falls,  has  a  center  span  of  840  feet, 
with  terminal  spans  at  each  end,  and  is  the  longest  arch  in 
existence,  though  several  larger  ones  have  been  projected. 
It  replaced  the  old  suspension  of  1868,  which  had  a  span 
of  1,268  feet,  and  is  the  third  bridge  to  occupy  the  site. 
The  deck  is  46  feet  wide  and  200  feet  above  the  water,  with 
two  car  tracks  in  the  center.  The  two  ribs  have  parallel 
chords  26  feet  apart,  with  pin  bearings  at  the  ends,  and  are 
30  feet  apart  on  centers  at  the  crown,  sloping  out  to  69  feet 
at  the  shoes.  The  main  arch  contains  1,825  tons  of  steel, 
and  the  whole  bridge  2,260  tons.  It  was  erected  cantilever 
similar  to  the  method  used  for  the  Mungsten  bridge,  and  was 
opened  for  travel  in  August,  1898.  Water  under  it  is 
believed  to  be  1 80  feet  deep. 


245 


FIGURE   222.      Stony   Creek   Arch,   British   Columbia 

The  Canadian  Pacific  Railway  crosses  Stony  Creek  in 
British  Columbia  on  a  steel  arch  340  feet  above  the  valley. 
The  location  is  very  picturesque.  The  sides  of  the  gorge  are 
so  steep  and  rocky  that  the  place  is  naturally  inviting  for  an 
arch.  When  first  building  the  road,  in  1885,  the  track  was 
carried  on  four  Howe  trusses  over  wooden  towers,  designed 
and  built  under  the  direction  of  W.  A.  Doane,  G.  H.  Dug- 
gan  and  T.  K.  Thomson,  engineers,  and  this  remained  in  use 
for  about  ten  years.  The  steel  arch  has  a  span  of  336  feet 
and  a  rise  to  the  under  chord  of  80  feet,  the  curved  trusses 
being  26  feet  deep  at  the  ends  and  20  feet  at  the  center.  The 
total  length  of  the  bridge,  including  the  terminal  spans,  is 
485  feet.  Arch  trusses  are  24  feet  apart  on  centers  at  the 
crown,  and  batter  out  one  in  ten.  They  are  pin  connected, 
but  all  bracing  is  stiff  and  riveted,  and  the  riveted  deck 
trusses  carrying  the  track  are  9  feet  apart  on  centers.  The 
weight  of  steel  in  the  arch  is  524  tons  and  in  the  entire 
structure  771  tons.  At  the  time  of  building,  the  Chief 
Engineer  for  the  railroad  company  was  P.  A.  Peterson, 
and  H.  E.  Vautelet,  Bridge  Engineer. 


247 


FIGURE  223.     Panther  Hollow  Bridge,  Pittsburgh 

This  bridge  carries  a  roadway  over  Panther  Hollow, 
a  ravine  about  120  feet  deep,  and  crosses  from  the  Phipps 
Conservatory  to  the  Speedway.  There  are  four  28-foot 
stone  arches,  two  at  each  end,  and  a  main  parabolic  steel 
arch  of  360  feet  and  45  feet  rise.  The  four,  three-hinged 
steel  ribs  stand  vertical  and  12^  feet  apart  on  centers,  and 
are  50  feet  deep  at  the  ends  and  5  feet  at  the  middle.  The 
bridge  is  615  feet  long  and  was  built  in  1896  at  a  cost  of 
$1  70,000.  The  road  is  40  feet  wide  and  two  1 0-foot  side- 
walks are  carried  on  cantilever  brackets,  both  roadway  and 
walks  having  asphalt  paving  on  steel  trough  flooring.  The 
end  pedestals  are  mounted  with  bronze  figures  of  panthers. 


249 


FIGURE  224.      Lincoln  Park,   Chicago,  Arch  Cantilever 

Lincoln  Park,  Chicago,  has  a  lagoon  nearly  a  mile  in 
length,  parallel  with  the  lake  and  only  a  short  distance 
away,  which  is  crossed  by  two  bridges.  As  small  boats 
and  launches  come  into  the  lagoon,  it  was  necessary  in 
constructing  bridges  to  build  them  high  enough  so  sail  boats 
could  pass  under.  The  arch  cantilever  form  as  shown  was 
adopted,  the  bottom  chords  of  the  end  brackets  conforming 
to  the  curve  of  the  main  arch.  The  west  end  of  the  bridge 
has  a  wide  set  of  steps,  while  the  east  end  is  reached  by 
stairs  leading  up  from  the  north  and  south.  It  has  an  orna- 
mental iron  railing  and  is  altogether  an  interesting  feature  of 
the  park. 


251 


FIGURE  225.      Coblenz  Railroad  Bridge 

The  bridge  over  the  Rhine  at  Coblenz  with  three  deck 
metal  arches  of  3 1 5  feet,  completed  in  1 864,  was  the  first 
braced  wrought  iron  arch  with  curved  parallel  chords.  The 
ribs  were  first  erected  on  end  hinges  and  after  completion 
the  ends  were  blocked  up  solid  against  their  bearings.  It 
carries  two  lines  of  railroad,  and  is  one  of  Hartwich's 
designs.  " 


253 


FIGURE  226,       Mexander  III  Bridge,   Paris 

This  is  the  widest  bridge  in  ]  'aris,  and  is  remarkable  for 
its  width  and  flat  arch  rise.  It  crosses  the  Seine  at  the  Fair 
Ground  and  connects  the  Champs  Elysees  and  the  Esplana- 
des des  Invalides.  The  width  is  40  meters  (131  feet),  one- 
half  of  which  is  roadway  and  the  remaining  half  divided 
between  the  two  walks  or  promenades.  There  are  fifteen 
lines  of  three-hinged  cast  steel  arch  ribs,  353  feet  long 
between  end  pins,  the  ribs  being  placed  slightly  less  than 
9^  feet  apart.  The  roadway  is  32  feet  above  water  and 
the  arches  have  a  rise  of  only  20|^  feet,  or  about  one-seven- 
teenth of  the  span.  It  was  named  in  honor  of  the  Czar  of 
Russia,  and  is  monumental  in  character,  as  there  are  at  the 
ends  ornamental  towers,  the  tops  of  which  are  75  feet  above 
the  road.  The  faces  of  the  arch  and  spandrels  are  adorned 
with  festoons  and  panel  work  in  iron,  and  the  balustrade  is 
rich  and  heavj'^  with  round  balusters  and  moulded  top.  At 
either  end  is  sculpture,  and  along  the  balustrades  are  orna- 
mental standards  supporting  clusters  of  lights. 


FIGURE  227.      The  Worms  Highway  Bridge 

The  highway  bridge  over  the  Rhine  at  Worms,  com- 
pleted in  1 900,  has  a  22-foot  roadway  and  two  7-foot  walks, 
supported  over  the  river  on  a  central  deck  arch  of  345  feet 
and  two  side  ones  of  330  feet,  the  chords  being  curved  to 
circular  arcs.  The  two  lines  of  braced  arch  ribs  are  two- 
hinged  crescent  shaped,  25  feet  apart  on  centers,  and  the 
weight  of  metal  in  the  three  river  spans  is  1 ,200  tons.  At 
the  ends  are  many  approach  masonry  arches,  and  at  either 
side  of  the  water  are  beautiful  portal  towers. 


257 


FIGURE  228.      The  Bonn  Bridge 

In  the  competition  of  1895  for  the  Bonn  bridge  over 
the  Rhine,  sixteen  designs  were  submitted,  and  the  one  pre- 
pared by  Reinhold  Krohn  and  Bruno  Moehring  was 
awarded  the  first  prize.  It  contains  a  central  614-foot  half- 
through  braced  arch,  with  a  307-foot  deck  arch  at  each 
side,  and  at  one  end  a  smaller  arch  of  106  feet,  all  ribs 
being  true  two-hinged  arches.  The  large  central  span  is 
divided  into  25 1- foot  panels,  and  the  rise  of  the  lower 
chord  is  97  feet,  while  the  highest  part  of  the  arch  is  136 
feet  above  water.  Trusses  are  vertical  and  29^  feet  apart, 
]5^  feet  deep  at  the  center  and  34|^  feet  at  the  ends,  the 
chord  sections  being  curved  to  true  circular  segments,  an 
expedient  which  adds  about  20  per  cent  to  their  cross  sec- 
tion. The  road  is  23  feet  wide  with  provision  for  two 
car  tracks,  and  at  each  side  is  a  1 1  -foot  walk,  the  whole 
being  paved  with  wood  blocks  on  galvanized  iron  buckle 
plates.  All  members  are  stiff  with  riveted  joints,  and  the 
arches  were  erected  on  false  work.  The  3,332  tons  of 
steel  cost  $257,000,  and  the  whole  bridge  when  completed 
in  1898  cost  $637,000. 


259 


FIGURE  229.      The  Dusseldorf  Bridge 

The  Dusseldorf  Bridge,  over  the  Rhine,  crosses  the 
water  with  two  through  braced  arches  of  595  feet,  with  a 
lower  chord  rise  of  90  feet.  At  one  end  are  three  approach 
deck  arches  of  167  to  200  feet,  and  at  the  other  end  a 
single  span  of  198  feet,  but  these  spans  are  of  very  different 
construction  to  the  central  bridge,  and  are  separated  from 
it  by  prominent  portal  towers  in  Renaissance  style.  The 
design  is  almost  above  criticism,  though  a  larger  center  pier 
might  have  been  more  fitting.  The  braced  arch  ribs  are 
two-hinged  circular  arcs  about  32  feet  apart  transversely, 
]6^  feet  deep  at  the  center  and  40  feet  at  the  ends,  sub- 
divided into  24-foot  panels.  The  crown  of  arch  is  129 
feet  above  mean  water,  and  the  deck  62  feet  above  the 
river  and  46-2-  feet  wide,  with  27-foot  road  and  two  1 0-foot 
walks.  Paving  is  with  wood  blocks  on  buckle  plates,  the 
maximum  grade  being  one  in  forty.  The  whole  bridge  is 
2,100  feet  long  and  the  total  weight  of  steel  is  5,130  tons, 
including  160  tons  of  railing.  The  metal  cost  $440,000 
and  the  whole  work  $905,000.  It  was  completed  in  1899 
under  the  direction  of  R.  Krohn,  Chief  Engineer. 


261 


FIGURE  230.      The  Rhine  Bridge  at  Mainz 

The  Rhine  Bridge  at  Mainz  crosses  two  arms  of  the 
river  with  three  and  two  spans,  respectively,  and  an  island 
with  six  spans  of  130  feet.  The  channel  spans  are  through 
tied  arches  of  306  to  382  feet,  similar  in  outline  to  that 
at  Bonn,  but  with  vertical  pier  reactions.  The  most  strik- 
ing parts  of  the  bridge  are  the  beautiful  portals  with 
their  minor  towers  and  stairs.  It  carries  two  tracks  and  two 
footwalks  and  was  completed  in  1904  at  a  cost  of 
$1,300,000. 


ii();H 


FIGURE  231.      The  Komhaus  Bridge 

The  Kornhaus  Bridge  over  the  Aar  at  Berne,  opened  in 
1898,  carries  a  41 -foot  highway  at  a  height  of  160  feet 
above  the  valley,  on  one  large  steel  arch  of  384  feet,  and 
five  smaller  ones  of  113  feet.  The  floor  is  on  a  2.7  per 
cent  grade,'  and  the  bridge  was  erected  on  full  timber 
centering  planked  over,  as  for  a  masonry  arch.  The 
largest  span  contains  two  braced  parabolic  ribs  without 
hinges,  divided  into  thirty- four  panels,  the  depth  being  5.2 
feet  at  the  crown,  increasing  to  14.7  at  the  springs.  The 
ribs,  which  have  a  rise  of  104  feet,  are  26  feet  apart 
on  centers  at  the  crown,  and  slope  out  at  the  rate  of  one 
inch  per  foot  to  43^  feet  apart  at  the  shoes.  Floor  beams 
are  1  7  feet  apart  and  the  road  is  paved  with  wood  blocks 
on  concrete  and  galvanized  buckle  plates.  The  large  arch 
is  approached  by  a  single  one  of  1  1 3  feet  at  one  end,  and 
by  four  of  the  same  length  at  the  other  end.  These  small 
ones  are  plate  box  girders,  36  inches  deep  with  about  38 
feet  rise.  The  weight  of  the  main  span  is  991  tons,  and 
the  whole  bridge,  1 ,995  tons,  the  cost,  including  founda- 
tions, being  $426,000. 


265 


FIGURE  232.      The  Tower  Bridge,  London 

For  twenty  years  or  more,  this  bridge  \vas  the  subject 
of  discussion  by  engineers,  architects  and  city  officials,  all 
of  the  designs,  and  especially  the  one  built,  being  very 
severely  criticized.  It  was  under  construction  from  1886 
to  1 894,  and  formally  opened  for  travel  on  June  30th.  The 
engineer  was  Sir  J.  Wolfe  Barry,  and  the  architect  Sir 
Horace  Jones.  The  steel  work  alone  cost  $1,685,000,  and 
the  entire  structure  $4,146,800.  The  clear  distance  between 
faces  of  towers  in  the  center  span  is  200  feet,  and  each  of 
the  two  end  spans  has  a  clear  width  of  270  feet.  Between 
the  towers  are  two  foot  bridges  with  a  headroom  under 
them  of  139  feet.  These  are  reached  by  elevators  and  are 
used  for  pedestrian  travel  when  the  bascule  leaves  are  open 
for  the  passage  of  ships.  The  total  width  between  parapets 
is  50  feet  on  the  open  span,  and  60  feet  on  the  side 
spans  and  approaches.  The  structural  parts  of  the  towers 
are  of  steel  enclosed  with  stone  casing,  and  this  feature  and 
the  method  of  cable  stiffening,  have  been  most  severely 
criticized.  The  north  and  south  approaches  are  1 ,000  and 
800  feet  long,  respectively,  and  the  total  length  of  the 
structure  is  2,640  feet. 


267 


FIGURE   233.      The   Conway   Suspension 

The  town  of  Conway  is  situated  on  the  east  bank  of 
the  Conway  river,  Wales,  and  is  the  site  of  the  famous  old 
Conway  Castle,  now  in  partial  ruins.  The  bridge  has  a 
span  of  327  feet,  and  was  designed  by  Thomas  Telford, 
and  constructed  in  1826.  On  account  of  its  proximity  to 
the  castle  it  was  made  to  harmonize  with  its  architecture, 
with  round  towers  and  battlements.  For  over  eighty  years 
it  remained  in  its  original  condition,  but  was  then  found 
insufficient  for  modern  loads,  and  was  strengthened  in  1904 
by  the  addition  of  new  anchorages,  cables,  suspension  links 
and  stiffening  girders.  A  new  6-foot  walk  was  also  added 
on  the  north  side,  the  cost  of  reinforcing  being  6,500 
pounds  sterling.  The  engineers  on  reconstruction  were  J.  J. 
Webster,  Chief  Engineer,  and  J.  F.  Jones,  Resident 
Engineer. 


20!-) 


FIGURE  234.      The  Budapest  Suspension  (1846) 

Budapest  has  two  very  fine  suspension  bridges,  perhaps 
the  most  beautiful  ones  in  existence.  The  new  Ehzabeth 
bridge  is  exemplary  in  all  its  parts  with  chain  cables  and 
rocker  towers.  The  bridge  illustrated  was  designed  by  W. 
Tierney  Clark,  and  was  built  during  1839  to  1845.  It  has 
a  central  span  of  600  feet,  and  a  total  water  way  of  1 ,250 
feet.  The  main  piers  show  artistic  treatment,  both  in  out- 
line and  detail,  and  the  combination  of  dressed  and  rock- 
faced  stone  work  is  pleasing.  Piers  are  symmetrical,  with 
cut-waters  at  both  ends.  The  walks  are  carried  out  around 
the  piers  on  brackets,  and  the  parapets  at  this  point  are  of 
stone,  conforming  with  the  other  masonry.  For  some  dis- 
tance above  the  roadway  the  towers  are  of  rock  faced  ash- 
lar, terminating  with  a  moulded  cornice,  above  which,  to 
the  main  cornice  they  are  dressed  stone  ashlar,  excepting 
the  ring  stones  for  the  roadway  arch,  which  are  rock-faced. 
The  upper  cornice  is  heavily  moulded  and  has  modillions 
in  its  design.  Over  the  sidewalks  at  the  piers  are  heavy 
ornamental  lamp  standards  rising  from  stone  bases  in  the 
balustrade.  At  the  four  corners  of  the  abutments  adjoin- 
ing the  river,  are  pedestals  surmounted  by  figures  of  reclin- 
ing lions.  Not  content  with  beautifying  the  bridge  itself, 
the  city  laid  out  gardens  on  the  river  bank  about  the 
entrance,  thus  making  a  proper  setting  for  the  structure. 


271 


FIGURE  235.      The  Brooklyn  Bridge 

For  many  years  the  most  striking  feature  in  the  land- 
scape about  New  York  was  the  old  Brooklyn  Bridge,  and 
although  there  are  now  three  others  over  the  East  River, 
the  first  remains  the  most  conspicuous  from  lower  New 
York  or  from  the  harbor.  It  was  started  by  John  A.  Roeb- 
ling  in  1870,  and  completed  in  1883.  The  towers  are 
1 ,595  feet  apart  on  centers,  and  the  floor  is  carried  by 
four  cables,  each  1 5f  inches  in  diameter.  The  end  spans 
are  each  930  feet  long,  and  it  has  a  carrying  capacity  of 
two  elevated  railway  tracks,  two  trolley  tracks  on  the  two 
1 8-foot  roadways,  and  a  center  1 5-foot  promenade.  Its 
total  width  it  85  feet,  and  the  length  of  the  New  York 
approach  is  971  feet,  the  Brooklyn  approach  being  1,562 
feet,  making  a  total  length  of  5,989  feet.  The  height  of 
towers  above  high  water  is  278  feet,  and  the  clear  head 
room  under  the  bridge  is  135  feet,  the  floor  grade  being  3^ 
feet  per  hundred.  The  original  cost  of  the  bridge  was 
approximately  $9,000,000,  and  the  land  $7,000,000  more, 
making  a  total  of  $16,000,000.  Previous  to  the  building 
of  this  bridge  the  longest  suspension  was  only  1 ,000  feet. 
Plans  were  recently  prepared  for  strengthening  it  by  pro- 
viding deeper  stiffening  trusses  and  an  entirely  new  floor 
system.  It  is  reported  that  not  less  than  $2 1 ,000,000  has 
been  spent  on  this  structure,  including  repairs,  land  and 
terminals.  It  extends  from  Park  Row,  New  York,  to 
Sands   and  Washington   streets  in   Brooklyn. 


27a 


FIGURE  236.      Sister   Island   Bridge,   Niagara 

Between  the  two  Sister  Islands  at  Niagara,  and  cross- 
ing the  rapid  water,  is  an  unusual  small  suspension  bridge 
shown  in  the  accompanying  illustration.  From  the  two  wire 
cables,  the  floor  is  suspended,  and  the  whole  is  stiffened 
with  wooden  trusses.  The  location  affords  the  sightseers 
a  good  opportunity  to  view  the  rapids.  Niagara  is  famous 
throughout  the  world  for  its  long  span  bridges  as  well  as 
for  its  wonderful  water  falls,  but  some  of  the  smaller 
bridges  display  more  art  than  the  larger  ones. 


275 


FIGURE  237.      Poughkeepsie  Bridge  over  the  Hudson 

The  Central  New  England  Railroad  Company  owned 
this  bridge,  and  leased  it  to  the  New  York,  New  Haven 
and  Hartford  Railroad  Company.  It  was  built  in  1 889 
with  two  anchor  spans  of  525  feet,  and  three  alternate 
cantilever  spans  of  548  feet,  with  two  end  spans  of  200  feet 
each.  The  east  approach  is  2,640  feet  long,  while  the 
west  approach  is  1,033  feet,  the  total  length  being  6,747 
feet,  and  the  track  212  feet  above  water.  It  was  arranged 
for  two  tracks  and  originally  had  two  lines  of  trusses  30 
feet  apart  on  centers,  but  in  1906  it  was  strengthened  to 
carry  heavier  loads  by  inserting  another  line  of  trusses 
midway  between  the  original  ones  and  adding  new  columns 
in  the  towers.  The  longer  approach  spans  were  also  rein- 
forced and  the  shorter  ones  replaced  by  new  plate  girders. 
The  reinforcing  was  done  at  a  cost  of  $1,300,000,  the 
amount  of  new  steel  being  1  5,000  tons.  The  trusses  have  a 
depth  of  37  to  57  feet,  and  the  towers  are  approximately 
100  feet  high,  standing  on  stone  piers.  The  water  under 
the  long  spans  is  60  feet  deep,  making  the  cost  of  false 
work  very  high.  Reconstruction  was  carried  on  under  the 
direction  of  Mace  Moulton,  Engineer. 


s"*  «<■;■»*»''.  ■JSK.wa-'^M'^l 


FIGURE  238.      Red  Rock  Cantilever 

This  structure  carries  a  single  line  of  railroad,  and  was 
completed  in  1890.  The  shore  and  river  arms  of  the 
cantilever  are  each  165  feet  long,  and  the  center  suspended 
span  is  330  feet,  making  the  total  length  990  feet.  It  was 
designed  by  J.  A.  L.  Waddell,  and  at  the  time  was  the 
largest  cantilever  span  in  the  United  States.  It  contains 
1,750  tons  of  steel  and  was  erected  in  eighty  days.  The 
trusses  are  25  feet  apart  on  centers,  and  there  is  a  clear 
under  head  room  of  41  feet.  It  crosses  the  Colorado  river 
and  connects  the  states  of  Arizona  and  California. 


279 


FIGURE   239.      The   Forth   Bridge 

Several  designs  for  a  suspension  bridge  to  cross  the  Firth 
of  Forth,  near  the  site  of  the  present  cantilever  were  made 
in  1818  by  James  Anderson  of  Edinburgh,  with  an  esti- 
mated cost  of  about  $1,000,000.  His  outlines  showed  three 
spans  with  a  space  beneath  of  90  to  110  feet  for  ships.  It 
was  not,  however,  until  1880  that  a  contract  for  the  con- 
struction of  a  stiffened  suspension  with  two  spans  of  1 ,600 
feet,  to  cost  $10,000,000,  was  awarded  on  the  plans  of 
Sir  Thomas  Bouch,  engineer  of  the  first  Tay  bridge,  but 
the  collapse  of  the  latter  after  only  two  years  of  service 
caused  the  contract  for  the  Forth  bridge  to  be  annulled  and 
new  plans  ordered  from  Messrs.  Fowler  and  Baker.  Foun- 
dations were  commenced  in  January,  1883,  and  the  struc- 
ture was  completed  in  1890,  after  a  period  of  seven  years. 
It  carries  two  lines  of  railroad,  forming  a  direct  connection 
between  the  north  of  Scotland  and  the  south  of  England. 
The  channel,  which  has  a  depth  of  218  feet,  is  crossed  by 
two  spans  of  1,710  feet  with  680  feet  anchor  arms,  between 
center  and  end  towers  270  feet  and  155  feet  long, 
respectively,  making  a  length  of  5,360  feet,  though  the 
total  length  of  bridge,  including  fifteen  spans  of  168  feet 
and  five  of  25  feet,  is  8,296  feet.  It  was  built  by  William 
Arrol  &  Company,  the  largest  number  of  men  employed  at 
any  one  time  being  from  4,000  to  5,000.  Clay  under  the 
foundations  is  loaded  six  tons  per  square  foot.  After  com- 
pletion it  was  found  that  the  maximum  center  deflection 
under  full  loads  was  six  inches.  The  bridge,  without 
approaches,  cost  $13,000,000,  or  $16,135,000  total,  equal 
to  $2,400  per  lineal  foot. 


281 


FIGURE  240.      Blackwell's  Island,  or  Queensborough  Bridge 

The  Blackwell's  Island  bridge  (1901-09)  is  a  continu- 
ous cantilever  with  unequal  channel  spans  of  1 , 1 82  and 
984  feet,  at  either  side  of  the  630  foot  anchor  span  over 
the  island,  the  west  and  east  shore  arms  being  469  and  459, 
respectively.  The  channel  trusses  are  connected  at  the  cen- 
ter without  suspended  span,  making  the  stresses  indetermi- 
nate. Two  lines  of  parallel  and  vertical  trusses,  60  feet 
apart  on  centers,  support  on  the  lower  deck  a  center  car- 
riageway, with  two  car  tracks  on  each  side,  the  outer  track 
the  trusses,  making  the  deck  86  feet  wide.  The  upper  plat- 
being  on  a  cantilever  extension  of  the  floor  beams  outside 
form  has  provision  for  four  elevated  railroad  tracks  between 
the  trusses  with  cantilever  promenade  at  each  side.  It  is 
the  first  instance  in  which  nickel  steel  has  been  used  exten- 
sively for  tension  members  and  pins,  and  it  contains  approxi- 
mately 13^  tons  of  steel  per  lineal  foot,  costing  5^  cents 
per  pound  in  place.  It  was  designed  by  the  Bridge  Depart- 
ment of  the  city  of  New  York;  contains  the  longest  can- 
tilever span  in  America,  and  is  proportioned  for  heavier  loads 
than  any  other  bridge. 


283 


FIGURE   241.      Cologne  Railroad  Bridge 

Crossing  the  river  Rhine  east  of  the  great  Cologne  cathe- 
dral, is  a  railroad  bridge  of  four  spans,  each  being  322  feet, 
and  the  whole  length  1 ,362  feet.  It  carries  both  railroad 
and  highway  in  separate  passages  between  the  three  lines  of 
lattice  girders.  It  was  built  during  the  years  1 855  to  1 859, 
and  is  47  feet  above  average  water  level.  Over  the  entrance 
on  the  Cologne  end  is  an  equestrian  statue  of  William  IV 
in  bronze,  while  at  the  other  end  is  a  similar  statue  of  Wil- 
liam I,  both  of  which  were  erected  in  1867.  The  bridge 
connects  Cologne  on  the  left  bank  of  the  river  with  Deutz 
on  the  right.  Square  masonry  towers  on  either  side  of  the 
entrance  are  ornamented  with  battlemented  cornice. 


285 


Figure   242,      Kehl  Railroad  Bridge 

This  bridge  crosses  the  River  Rhine  at  Kehl,  about  two 
miles  from  Strassburg,  Germany,  and  carries  two  lines  of 
the  Baden  State  Railway.  It  was  built  during  1858-60, 
and  was  designed  by  Keller.  There  are  three  main  lattice 
girder  spans  197  feet  m  length,  continuous  over  the  piers, 
and  each  span  has  three  girders  with  single  lattice  webs, 
while  at  one  end  are  four  additional  spans  of  85  feet  and  a 
draw.  The  footpaths  at  the  sides  are  supported  on  brackets 
from  the  outer  trusses,  and  the  outside  length  is  303  meters. 
Gothic  portals  at  the  entrance  are  fine  examples  of  orna- 
mental iron  work,  and  there  are  also  iron  towers  over  the 
river  piers.  The  portal  arches,  with  their  statues  and  crosses, 
are  suggestive  of  cathedrals.  In  ancient  times  the  building 
of  bridges  was  considered  a  sacred  duty,  and  the  work  was 
often  entrusted  to  priests,  who  were  given  the  name  of 
Pontifeces.  It  is  appropriate,  therefore,  that  decorative 
features  should  sometimes  be  ecclesiastical  in  character  in 
memory  of  the  traditions  of  early  bridge  building. 


287 


INDEX  OF  PERSONS 


PAGE 

Adrian 6 

Agrippa 5,   1  75 

Anderson,  L.  W 219 

Anderson,  James 281 

Angelo,  Michael 181 

Antonio    da    Ponte 181 

Arrol,  Sir  William  &  Co.  .  .281 

Augustus,   Caesar    5 

Babb,  Cook  &  Willard 217 

Baker,  Sir  Benjamin.  .  .  183,  281 

Barry,  Sir  John  Wolfe 267 

Bates  &  Rogers 211 

Bayley,  J.  P 65 

Beach,  Capt.  L.  H 155 

Biddle,  Col.  John 155 

Boiler  &  Hodge 239,241 

Bouch,   Sir  Thomas 281 

Buchholz,  C.  W 191 

Burr,  Wm.  H 25,  197 

Clark,  W.  Tierney 271 

Concrete     Steel      Engineering 

Co=    Preface 

Cruttwell,   E 183 

Cullen,  F.  J 211 

Doane,   W.    H 247 

Douglas,  W.  J 155 

Duggan,  G.  H 247 

Dunne.  W.   M 209 

Eads,  Capt 31,  84 

Emperger,  F.  von 157 

Fidler.    T.    C 71 

Fitzgerald,  Mr 1  89 

Fowler,   Sir  John 281 

Hartwich,  M 253 

Hastings,  Thomas    .  .  .  Preface,   1 

Hewett,   W.    S 193 

Hinckley,   H.   V 227 

Ingersoll,  CM 197 

Jervis,  John  B 187 

Jones,  J.  F 269 

Jones,  Sir  Horace 267 

Keepers  &  Thacher 227 

289 


PAGE 

Kellar,  George 1  25 

Krohn.  Reinhold    .  ..  .259,   261 

Laing,  T.  E 65 

Landor,   E.   J 211 

Linden  thai,  Gustav 72,   89 

Luten,  D.  B 235 

Matthyssens,  M.  H 65 

Meigs,  General  M.  C 185 

Michael  Angelo 181 

Moehring,    Bruno    259 

Moisseiff,   L.   S 197 

Moorsom,  Captain 65 

Moulton,  Mace 277 

Mueser,  Wm Preface 

Newcomer,   H.   C 155 

Newton  Engineering  Co  ....  1  5  1 

Newton,  Ralph .  .  .    61 

Olmstead,  F.  L.  &  Co 147 

Osborn  Engineering  Co 211 

Oudry,  M 90 

Palmer  &  Hornbostel 131 

Paine,  Thomas 3 

Parker,  George  A 23 

Pelz,  Paul 

Preface.  243,  245 

Perronet,    Jean   R 1 08 

Peterson,  P.  A 247 

Quimby,  H.  H 199 

Rennie,  John 113,  183 

Rennie,  George 183 

Reynolds,  A.  M 217 

Roebling,  John  A 273 

Roper,  Oscar 65 

Rusche,  J.  P 219 

Sanne,   Oscar    141 

Schwedler,  Herr 91 

Scofield  Co 213 

Shaw,    Edward   S 61 

Shepley,  Rutan  &  Coolidge .  . 

143,  145 

St.  Benezet 6 


290 


INDEX  OF  PERSONS 


PAGE 

Steiner,  Charles 81 

Stephenson,  George 32 

Symonds,  Capt.  T.  W 243 

Telford,  Thomas  .  ..14,  95,  109 

Thacher,  Edwin 227 

Thomson,  Thomas  K 247 

Trajan    1  02 

Tubesing,  W.  F 219 

Turneaure,  Prof.  F.  E 151 


PAGE 

Tyrrell.  H.G 43,  52,  53 

55,  64,  71,  72,  76.  79,  167 

Vautelet,  H.  E 247 

Waddell,  J.  A.  L 279 

Walker  &  Kimball 147 

Warren,  Whitney Preface 

Webster,   George  S 1  99 

Webster,  J.   J 269 

Witmer,  Mr.  and  Mrs 17 


GENERAL  INDEX 


PAGE 

Abutments 113 

Alcantara  Bridge 29,  1  79 

Alexander      III      Bridge      at 

Paris 82,255 

Algoma,  Bridge  in 54 

Anchorage  for  Cables 1  00 

Approaches 88 

Arches,  Metal. 75 

Arches,  Type 11 

Arches,  Form  of 84 

Architects,  Services  of 4 

Architects,      Co-operation     of 

24,  26,  38 

Art  Standards 19 

Art  Standards,  Absence  of .  .    24 

Art,  Cause  for  Lack  of 24 

Artistic  Bridges,  Reasons  for .     1  6 

Atlantic,   Bridge  over 12 

Auteuil  Viaduct,  Paris ...  30,  32 

Avignon,  Bridge  at ...  * 6 

Balustrades,  Designs  for ....  1  1  7 

Bascule   Bridges 58,  59 

Beam  Bridges 50 

Belle  Isle  Park  Bridges .... 
37,  137,  164 

Blackwell's  Island  Cantilever .  283 
Bonn   Bridge   over  the   Rhine 

23,80,259 

Boston  Bridges lA,\A'b 

Boston  Public  Garden 171 

Britannia  Bridge 32 

Brooklyn  Bridge 1 ,211) 

Budapest  Suspension 271 

Cabin  John,  Washington.  .  .'.  185 

Cables 97 

Cahors,  Bridge  at 30 

Cantilever  Bridges 67 

Cantilever   Bridges,  Views  of 

277  to  283 

Cernavoda  Cantilever 69 

Chatsworth  Bridge,  Ejigland.  195 

Chicago  Swing  Bridges 64 

291 


PAGE 
Chinese  Bridge  Builders  ....  5 
Chord  Outline  on  Cantilevers  .  69 
Clearance  under  Bridges.  ...  56 
Cleveland     Concrete      Bridge 

46,205 

Coblenz  Steel  Arch 253 

Cologne,    Designs   for 65 

Cologne,    Truss    Bridge    over 

Rhine  at 285 

Color  of  Materials 125 

Columbian  Park,  Lafayette  ..165 
Competition,  Result  of .  .  .  .24,  25 

Como  Park,  Bridge 161 

Concrete  Beam  Bridges .  .  .51,  52 
Concrete     Park     Bridges 

149  to  165 

Conformity    with     Environ- 
ments        20 

Contrast    42,  46 

Conway  Suspension 269 

Croton    Aqueduct    Bridge...  187 

Cubzac   Suspension 92 

Curve  of  Arch 107 

Dayton  Bridges 211 

Derby  (Conn.)   Bridge 237 

Deck  Bridges 36,  41 

Decks,  Number  of.  .  .56,  57,  59 
Deck    and    Springs,    Relative 

Position  of 11 

Deck  of  Masonry  Bridges .  ..103 

Design,    Principles   of 38 

Detroit,    Bridges    at....  3  7,    137 

Dim.ensions,  General    41 

Dominion  Bridge  Co 71 

Dredge  Suspension 91 

Duesseldorf    Bridge    over    the 

Rhine .80,  261 

East-on  Suspension  Bridge.  .  .  93 
Echo  Bridge,  Newton,  Mass .  1  89 
Economic    Use    of    Materials 

20,21 

Eden   Park  Arch 157 


292 


GENERAL  INDEX 


PAGE 

Elizabethtown  Bridge    53 

Ellipse 1  08 

Emerichsville  Arch   Bridge.  .225 

Engineers,   Training  of 24 

English  Channel  Bridge 12 

Environment,  Conformity  with 

20,42,47 

Expressiveness 42,  44 

Features  of   Bridges 29 

Financial  Lim'tations 24 

Florence,  Italv,   Bridges .  .  29,  30 

Forest  Hills,  Boston 145 

Forest     Park     Entrance,     St. 

Louis    43 

Form  of  Metallic  Arches ...    84 

Forth    Bridge    281 

Garfield     Park     Suspension 

139,   173 

Garabit  Arch    83 

discard  Suspension   . 91 

Gothic  Portals 45 

Grade  of  Bridges 56 

Grand   Avenue    Bridge,    Mil- 
waukee    =  1  03 

Grand  Rapids  Concrete  Arch  .219 
Grand     Tower     (111.)     Con- 
crete Bridge    207 

Green    Island    Bridge,    Niag- 
ara        231 

Grosvenor  Stone  Arch 1  04 

Grunenthal  Metal  Arch 77 

Halsted   Street   Lift   Bridge.  .  65 

Harmony    42,  46 

Hartford  Bridge 31 

Hasty      Construction,      Effect 

of    24,25 

High     Bridge,      New     York 

City    187 

Hindrances  to   Art 24 

History   of    Bridge    Engineer- 
ing        73 

Hell  Gate  Arch 89 

Hudson    Memorial,    Proposed 

Steel  Arch    239,241 

Hudson   Memorial    Bridge 

39,  197 

Hyde  Park  Bridge 159 

Importance   of    Bridges 9  ' 


PAGE 
Indianapolis   Concrete   Arches 

221,223 

Interlaken   Bridge,   Minneapo- 
lis     193 

Jamestown      (Va.)      Concrete 

Bridge     213 

Jordan  River  Bridge 52 

Karlsbruecke  at  Prague 177 

Kehl  Bridge  over  the  Rhine.  287 

Kinds  of  Bridges 32 

Kornhaus  Steel  Arch  at  Berne 

86,265 

Lack  of  Art,   Causes   for.  .  .    24 
Lafayette    (Ind.)     Bridge.  .  .  1  65 
Lake     Park      (Milwaukee) 
Arch  151,  169' 

Legal  Hindrances  to  Art ...  24 
Lehigh  River  Suspension.  ...  93 
Lincoln  Park  Steel  Arch.  86,  251 
Literature  on  Artistic  Design .    24 

Lift  Bridges    65 

Location,  Effect  on  Design.  .  28 
Log  Arch  at  Washmgton .  .  .  1  35 

London  Bridge 13,  183 

Longwood  Bridge 143 

Long  Spans 35,  41 

Lubeck  Swing  Bridge 65 

Madison  (N.  J.)  Park  BHd^^e 

43,  167 

Magnitude  of  Bridges 11 

Ma-nz    Steel    Arch    over    the 

Rhine 263 

Manhattan  Suspension 96 

Marion  County  Concrete 

Span     215 

Masonry  Bridges 101 

Masonry  Park  Bridges 

139  to  147 

Materials,      Combinations     of 

42,48 

Materials,  Economic  Use  of .  20 
Materials,  Absence  of .  .  .  .24,  27 
Maumee  River  Bridge,  Water- 

ville    235 

Memorial  Bridges 17 

Metal  Arch  Bridges.  .239  to  265 
Metal     Arch     Park     Bridges 

167  to  169 


GENERAL  INDEX 


293 


PAGE 
Metal  Bridges,  Beginning  of.  3 
Middletown  Swing  Bridge  ...  64 
Minneapolis  Park  Bridges.  .  .  133 
Monterey  (Mexico)  Bridge.  .  31 
Montreal  River  Bridge..  ...    54 

Motive  in  Design 41 

Movable  Bridges 56 

Mungsten  Arch 83 

Nature,  A  Guide  in  Design .  38 
Newark     (N.     J.)     Concrete 

Arch     217 

Newell  Avenue  Bridge,  New 

York     1  63 

Newton  Creek  Bridge 61 

New  York  City  Bridges.  .  1,  2,  6 
Niagara  Arches  ...  78,  89,  245 
Niagara  Falls  Concrete  Arch 

231,233 

Niagara  Suspension 275 

Northampton  (Mass.)   Bridge    1 7 
North     River     Bridge,     Pro- 
posed     97,98 

Northwestern  Avenue,  Indian- 
apolis     223 

Ogden  Viaduct,  Proposed.  55,  56 

Oporto  Arch    83 

Ordish  Suspension 91 

Ornament,    Use    of.  .  .20,  42,  49 

Ornament,   Degree  of 35 

Ornamentation  of  Cantilevers .  73 
Ornamentation     of     Metal 

Arches    89 

Outline,  Pleasing 20,  22 

Panther    Hollow     Bridge, 

Pittsburgh 249 

Paris  Bridges 1  3,  30,  255 

Parapets    117 

Park   Bridges    43 

Park,  Bridges,  Concrete .... 

149  to  165 

Park  Bridges,  Masonry 

139  to  147 

Park   Bridges,    Metal   Arches 

167  to  169 

Park  Bridges,  Rustic.  131  to  137 
Park     Bridges,     Suspension 

171  to  173 

Persia,  Bridges  of 30 

Peru  (Ind.)  Concrete  Arch .  .229 


PAGE 

Philadelphia  Bridges 31,44 

Piers     41 

Piers  of  Masonry  Arches.  .  .  1  09 

Piers  of  Metal  Arches 87 

Pins     or     Hinges     for     Metal 

Arches    81 

Plauen,  Arch  at 34 

Pont  du  Gard 5,  1  75 

Ponte  Vecchio,  Florence.  ...    29 

Pontifex  Maximus 45 

Portal    Decorations 32 

Potomac   River   Bridge,    Pro- 
posed        40 

Potomac  Memorial,  Washing- 
ton, D.  C .  .201,203,243,245 
Poughkeepsie  Cantilever  .  .  .  .277 

Prague,    Bridge   at 91 

Primitive  Bridges 9,    10 

Professional  Vandals 25 

Progress  in  Bridge  Building .  .     10 
Purpose,  Exhibition  of  .  20,  21,41 

Quebec  Bridge 12,  68,  71 

Queensborough  Bridge 68 

Railings    122 

Railroads,    Effect    on    Bridge 

Building 3 

Railroad    Bridges    as    Proto- 
types      24,  27 

Reasons  for  Artistic  Bridges .     1  6 

Red  Rock  Cantilever 279 

Reinforced    Concrete    Bridges 

197  to  237 

Relation  of  Bridges  to  Human 

Progress    13 

Rialto,  The,  at  Venice.  .29,  181 

Rigid  Suspensions 1 00 

Rimini,  Bridge  at 5 

Roads  and  Bridges 14 

Roche   Bernard   Suspension .  .    95 
Rock    Creek    Bridge,    Wash- 
ington     155 

Rocky  River  Arch,  Cleveland 

205 

Roebling's  Suspension    94 

Rome,  Bridges  at 1  3,  33 

Roman  Bridges 5,6 

Ruskin's  Rules  of  Art 49 

Rustic  Park  Bridges.  .131  to  1  37 
Rustic  Bridges 9,  1  0 


294 


GENERAL  INDEX 


PAGE 

Saintes  Bridge 48 

Salmon  River  Cantilever .  .71,  72 
Salmon  River  Steel  Arch.  .  .247 
Salmon   River   Viaduct,    Pro- 
posed        55 

San  Francisco  Park  Bridges  .131 
Schwedler's    Design    for    Co- 
logne         91 

Schenley  Park  Arch 106 

Seine  River  at  Paris 82 

Shaoe  of  Masonry  Arches.  .107 
Shelters  at  Movable  Bridges.    32 
Simplicity,  A  Principle  of  De- 
sign     42,45 

Sister   Island   Suspension,    Ni- 
agara     275 

Skevs^  Crossings 50 

Spandrel    Framing    of    Metal 

Arches    75 

Spandrels  of  Masonry  Arches .  1  04 

Span   L'mits    12 

Spans,  Number  of,  in  Suspen- 
sion Bridges    93 

Springs     of     Arches,     Eleva- 
tion of 86 

Springs  of  Masonry  Arches  .  .  1  08 
Spuyten  Duyvil  Creek  Bridge   33 

St.   Angelo,   Rome 30 

St.  Chamas  Bridge 29 

St.  Louis,  Mo 43 

Standards  of  Art 19 

State  Supervision,  Absence  of 
24,28 

Steel  Bridges,  Objection  to .  .    34 

Steel  Structures 50 

Stiffening   of   Cables 99 

Stockbridge  (Mass.)  Concrete 

*       Arch     1 49 

Stone  Arch  Bridges.  .  1  75  to  195 
Stony  Brook  Bridge,  Boston.  147 

Surface  Finish 125 

Suspension  Bridges,  History  of  90 
Suspension     Bridges,     Illustra- 
tions of 267  to  275 

Suspension  Bridge  Type.  ...    91 


PAGE 
Suspension      Park      Bridges 

171    to  173 

Sw^ing  Bridges 63 

Symmetry 42,  45 

Symmetry,   Absence  of 24 

Symmetry  of  Approaches  ....  88 
Symmetry,    Lack   of  in   Stone 

Bridges     1  02 

Terminals,  Railroad 26 

Terre  Haute  Concrete  Arch  .  209 
Thermopylae  Metal  Arch.  .  .  85 
Topeka  Concrete  Arch.  106,  227 
Tower  Bridge,  London.  .92,  267 

Towers   of   Bascules 61,  62 

Towers  for  Metal  Arc'^cs.  .  .  87 
Towers  for  Suspension  Bridges 

93,97 

Training  of  Engineers 24 

Transporter  Bridges 66 

Trestles,  Steel 54 

Truss  Bridges  .  .  .53,285  to  287 

Type,   Selection  of 34 

Ugly  Bridges    18 

Union  Park,  Chicago 153 

Value    of    Bridges    in    Amer- 
ica         11 

Venice  Bridges 1 ,  29 

Walnut   Lane   Bridge,   Phila- 
delphia      1  99 

Washington,  Proposed  Bridge 

at     1  7,  40 

Washington     (D.     C.)     Pro- 
posed Memorial  at.  .  .  243,  245 

Waterville,  Bridge  at 235 

Wayne   Street   Bridge,    Peru, 

Ind ...229 

White   River   Bridge,   Indian- 
apolis   221 

Williamsburg     S  u  s  p  e  n  - 

sion  Bridge 94 

Wissahickon  Creek  Arch  .  ...  1 9 1 
Worms,  Highway  Steel  Arch  .257 
Yellowstone  Park  Arch  ....  1  5  7 
Yunnan  Steel  Arch,  China .  .  84 
Zanesville  Concrete  Arch ...  2 1  1 


BOOKS 

BY 
HENRY  GRATTAN  TYRRELL,  C.  E. 


CONCRETE  BRIDGES  AND  CULVERTS 
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HISTORY  OF  BRIDGE  ENGINEERING 

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ARTISTIC  BRIDGE  DESIGN 

A  Systematic  Treatise  on  the  Design  of 

MODERN  BRIDGES  ACCORDING  TO  AESTHETIC  PRINCIPLES 

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